Returned an IPhone 12mini mid-December and a month later my account still isn't updated to reflect return. Anyone experiencing USPS delays?

I upgraded to an IPhone mini12. When I received it in the mail, I didn't even take it out of the box. I could see it was way too small for my eyes. Called ATT, got a return label, and mailed the IPhone mini back to them. I don't have a copy of the label to track it. My ATT account won't let me upgrade to a larger cell phone because it says I need to pay the $600 plus for the mini 12. Is anyone else having lengthy delays sending back cell phones to AT&T?