Paint Help

[shaney b]

ive recently brought a gsi bumper which was fair to say it was in a pretty ruff state but i got on with sanding it down n prepping it for painting it all went well apat from when the bumper was painted with halfords paint after that i started to see little cracks within the pait that i couldnt see when it was sanded down i repeated the process and tried again but i got the same results, i was going to try a third time but thought id ask if anyone knew a cheap bodshop around the birmingham area that would do it for me as i cba to do it myself. or if anyone knows a paint removing product that allows me to spray over the top of it i would be grateful if you could help me

thanks