I have a pair of Sony MDR-1000X that I received as a gift in spring 2017. The serial number of these headphones falls within the range of 5000001-5256984 which means that they have weakened headbands. The headband has now cracked, and I cannot use them anymore. I have tried to get in touch with Sony customer support on the phone, but they don’t seem to know anything about this issue and insist that the item is out of warranty. What should I do?