AT&T Service Failure - Refund for Incorrect Billing

I traveled to the United Kingdom from 5/17/2019-6/1/2019. The day I left the US I added an international package to my account. Three days into my trip my phone was shut off because of incorrect international overages. I called back and was told the international package was never turned on, but that AT&T did have a record of my call and the request and it would be fixed immediately. My phone continued to work for the remainder of my trip and I assumed the international package was added correctly. 

I returned to the US and on my next two bills I was over charged a combined total of $445.24 for international usage. It was unclear if the international package was still not applied to my account or if it was incorrectly applied or ignored. 

I have called AT&T customer service seven times in the last two months. The first calls were to alert them to the incorrect charges to my account. I was first told they would be fixed and that my account would not be charged. Then my account was charged. On two different billing cycles. I called back asking for a refund for the amount, was given a case number and told the refund would take five days. That was fifteen days ago. I have called back every other day since then. I've been told three separate times that the refund would take five days and all of those dates have come and gone without a refund. I have been transferred to multiple supervisors and departments and have not been given a clear answer once. 

Today I was on the phone for an hour and a half and have spoken to three separate reps. I have been told that the amount is too large for a refund, which does not make any sense to me. I am well aware of how large the amount is since it is my money. I should not have been charged and they charged me anyways. Of the three reps I spoke to today alone the first told me they couldn't give me an exact refund date, the second told me that I would be getting a credit and not a refund, and the third rep told me she was from the Loyalty program and could not help me but would transfer me to the International Department. Then the call was disconnected. 

Each one of these calls have taken anywhere from 30mins to 90mins. I have spoken to over half a dozen representatives and have not been given the same answer. My case number does not seem to matter and every time I call I am forced to relay the same information over and over . I am frustrated beyond belief. 

Can anyone from AT&T or on these board please assist me? This is becoming absurd. I have begun reaching out via social media and plan on filing a complaint with both the FCC and BBB if I my valid request for a refund are continued to be unanswered.