Complaint about wireless

What is the best phone number to call to file a complaint?  The loyalty and retention people are the problem and a very expensive one (wireless).  I've done everything for months (MONTHS) to resolve my issues and get reimbursed for a return, for your wireless service not working, for your people blaming my equipment, causing me to file and insurance claim to replace my phone, finding that phone had no problems, your people then convinced me to upgrade my phone (blaming now the new phone), I deactivated the new phone when I had the old phone (s) diagnosed and the issue and with the new phone, were network failures!  On day 14 I was told that your loyalty and retention area had extended the return period on my new phone to 30 days, that was honored but should never have happened, I wanted to leave AT&T and buy that exact phone at another carrier and by the time it took for L&R to convince me to upgrade and that I could return the phone by mail that phone was no longer carried by the new carrier, the manufacturer or retail stores... I asked L&R to use the huge credit balance in my account due to your network failures to pay off the new phone and unlock it so I could take it with me... they informed me that the 30 return period was wrong, they got an exception so I could return the phone, but could not unlock it... fast forward the phone was returned a month ago, I have not received my refund, when I called to check on it, they told me they'd put it back on the card I used to purchase the device, they didn't, they further credited my account that had a HUGE credit anyway... this caused overdraft fees as i was told the refund would happen that day several times, and when I contacted L&R again, I found that the phone I wanted unlocked could not be put back into inventory at ATT because of the weird way your people told me to return it so they destroyed the phone that I asked you all to let me keep and I still haven't gotten my money back!!!! this is just my experience from Aug. 2022 until now, Nov. 16, 2022.. the issues really date back to FEb. 2020 and have cost me time, money and business!