I am afraid you are out of luck - MAACO is an economy paint and body shop --- when you pay $500 (or anything less than $1500) for a paint job that is what you get - they will simply scuff, feather large chips if you are lucky, degrease, tape, mix & shoot paint, remove masking, do a basic clean and deliver the car. They will not use anything rougher than 400 grit usually. Sanding scatches like you are describing indicate that the bodywork underneath was completed to no finer than 220 grit - prep work is on the person who did the body work. The average body shop I have encountered will charge $3500 - $4500 for a decent paint job which includes some "ding" repair, chip repair, etc.. but NO BODY WORK or rust repair whatsoever - just basic removal and installation of SOME trimwork for that price. When I paint a car I do not topcoat until I have gone over the WHOLE car with compatable primer and long board, re-prime, longboard again, then re-prime, block, fill small imperfections in between each prime, and finally wet sand the last coat of primer down to 800 grit. After the paint has cured I will hand wet sand the car with 800grit, 1000grit, 1500grit and then 2000grit and finally 3 different grits of rubbing and polishing compounds. That is a tremendous amount of work and cost of materials for JUST $500. I have painted many cars in the past and 90% of the quality of a final paint job occurs before the paint goes on. I cannot paint my own car at my own house for $500 due to cost of materials - tape, masking, sanding paper, hardener, thinner, pigmant, solvents, etc.... all add up very quick. I know I am not the best body and paint person and will NEVER be but this is what it takes to get a decent looking job. I have been in the auto body repair and insurance industry for 13 years and have been doing my own body and paint work for well over 20 years on a hobbist level. What you are describing sounds like a incompatablility with materials. NO body shop will guarantee an individual's prior body or prep work and if you read the paperwork you recieved from the shop it say that usually. Lots of rattle can paint is high in solvent content that takes months to fully evaporate out and if it is painted on top of with an incompatable paint it will surely have a solvent pop problem. Also that thin red cream backyard bodymen use to fill in minor pin holes is nothing but a problem waiting to happen. It will do EXACTLY as you describe once paint is on top of it and it often falls out in very short order. Bondo is not a bad word - if mixed, prepped, and used properly it can work wonders. Almost all NEW cars have BONDO in them when brand new on the lot. 30% of all BRAND NEW cars have also been damaged in some way prior to being sold as new and most are repaired with bondo and you never know it even 15 or more years later. It is very important to use a complete system of prep, prime, topcoat chemicals so they will not produce an unwanted chemical reaction later. If you do not use the same brand for every step WATCH OUT! unless you know what you are doing you should not mix up different brands and types of that stuff. I do not want to discourage you - I know about working with a budget (every one of my cars has a budget) and you CAN have a great looking final product for not a lot of money IF you take your time, use the right products, read the labels and understand what is going to happen. It is helpful to talk to the final paint shop to find out what brand and type products they use in their "system" and then you can use the same compatable products during your end of the job. Always use a long board, sanding block, AUTOMOTIVE primer (keeping in mind what topcoat will be - enamel, epoxy, etc... so it does not solvent pop), give plenty of evaporation time - at least a month - and never take a car to paint without checking your work with sanded off guide coats and finish prepping to about 600 grit to avoid sand marks. Also - Never use products containing silicone such as rubber dressings etc... as they will soak in to paint an NOTHING will stick once that happens. Once the car is painted you WILL get chips. Do not let this ruin your day - chips can be taken care of with touch up paint or an airbrush. This also applies to your problem areas you have now. You can sand out the damaged area, clean and prep, apply filler as needed, apply paint with a "melting agent" after proper prep work to only the immediate damaged area and then mask around it and wet sand it down after the touched up area has cured for several days. Concentrate on the touched up area by gently sanding it down with 800grit, 1000grit, 1500,grit and then 2000grit - you can even get 3000grit to burn the edges of the touched up area into the surrounding paint before final compounding, polishing and buffing. This can be done to both single stage and base/clear paint. (You can tell base/clear or single stage with several methods if you don't know what your car was painted with - rub it with some fine sand paper and if it comes off white it is base/clear and if it comes off body color it is single stage. If your car is light blue, white, light yellow or some other light color that it is not possible to tell if it is coming off white or not simply rub the smooth portion of an aluminum pop top can tab on the paint after wiping it clean and dry - if it leaves a light pencil lead type mark it is single stage and if it does not then it is base/clear (unless there is a good coat of wax) Good luck with your project.