REFRIGERATOR PART REPLACEMENTS

We have a Sub-Zero 610 refrigerator built in 2002. The evaporator coil has been replaced twice because of freon leaks. The first time, parts and labor were covered (within 5 years of purchase) and this was in response to a recall. The second time was diagnosed after the unit continued to lose freon. While parts were covered, there was a $400.00 service charge. We also had to pay $95.00 for a freon top off while the problem was being diagnosed. The technician tells me that Sub-Zero has a problem with their copper evaporator coils ... The first time the coil was replaced, a copper one was supplied by Sub-Zero, which also failed. Now we have another replacement, and only time will tell...