I’m being charged for a phone iPhone X that your warehouse lost

I have reached out several times about being charged for an iPhone X they had been returned. It was delivered to your warehouse on 10.31. I had one rep tell me I would be credited back for the lost device charge in 12.2 by 9 am (I spoke to her on 12.1 at 8am). 9 am passed and still no credit. I called back on 12.2 around 7 or 8 and spent almost 2 HOURS on a phone with a rep who was trying to help me out. He said that he had to escalate it to his supervisor's SUPERVISOR and would follow up with me today 12.3. The entire day has passed by and I haven't received one phone call, email, or text! I'm am
LIVID! And I'm tired of being lied to. You're warehouse misplaced the phone and I refuse to pay almost 1100 for a phone that was returned back. I need this resolved ASAP!