A month ago, I sold a Verizon iPhone 6 on Swappa, a device I used with AT&T for a month. Now a month later, the buyer says its locked, sent me the IMEI and told me I need to unlock it. I sent him Verizons website unlocking policy which clearly states all 4G LTE devices are unlocked already. Is there anything else I can do? He's going to open a claim on paypal and this is ridiculous.