Here is the way I handled two similar situations. After the ban died I bought several full cap .45 mags. A week or two later I noticed the floor plate on one was split and was coming off. I took off the floor plate, put it in a padded envelope with a letter stating what had happened, and sent it to HK CS for replacement but also offering to buy it if there would be any charge. Then, just forget about it for a month or so. About 3 weeks later a new floor plate showed up, no charge, no invoice, no anything, just a floor plate. Made me happy as a clam.
Before the above I had a USC mag in which the follower was binding and actually broke off the plastic around the steel liner in the feed lips when the follower first bound and then released. Same thing. Sent it to them with a letter of explanation, three or four weeks later a new mag showed up.
They have one CS guy working there and he is overwhelmed. I have found it best to not call them unless it is absolutely necessary.