the thing is that they use very agressive compound and the paint is already thin due to aging and half of the old paint jobs didnt have a clearcoat so u r eating the color away and after a while the primer will be exposed. thats what happened to my car, this is most important for the red suzuki cars. if u want paint correction buy meguiars ultimate compound, it is far less agressive than the desi crap.
as for the ac, replace the condensor fan and refill the gas, but dont get that gas which the workshop guys have ask them where they buy and get it from there. the best gas costs around 1600 per kg, you will need around 1300 worth of that gas. both things were done to my car and cooling is around 30% better