Poor Repairs Workmanship at Autobahn BMW - Paint cracks within a month

Took my car for repairs to the Left Back light and Bumper in October. in Early December I started to notice the paint at the bumper starting to crack... Im disappointed at the poor workmanship at BMW Autobahn following the aweful service they has given. They still havent answered my emails about this and i want a new bumper from them.... my car is still fairly new... not going to roll around in a cracked mini cooper.