ATT will Lock you into a 6 month prepaid contract without your knowledge... BE AWARE

After over 10 hours of calls and research... the end result was ATT denied my unlock request for my FULLY BOUGHT AND PAID FOR IPHONE Xs purchased from Best Buy

I am currently out of the country and will literally have to FLY back to the US to return my phone...  Absolutely, completely RIDICULOUS that you can be locked into a contract without any time of acknowledgement.  I'm pasting my complaint I posted on the ATT facebook page below...

There is a 27+ page thread on the best buy forum for this exact issue... which best buy's only response is to return the phone if it's within 14 days... if it took longer than 14 days to realize what happened... then they will not help you at all and don't care.

TL:DR
ATT locked my phone I purchased at Best Buy at full retail price with no contract, agreement, subsidy or anything else... Neither the Best Buy employee, nor at ANY point during the process of setting up at transferring my old phone data to my new phone was I made aware by acknowledging any terms, conditions or anything else that I would need to use ATT on THAT DEVICE for 6 months. I have used ATT for over a decade and ATT prepaid for over 3 years... this whole experience has been Atrocious and all Best Buy has offered is "sorry, they should have told you"

Good Morning, I have called 5 times to customer service, with an approximate total time on the line with just ATT customer service of 4 hours, with no resolution. The issue is as follows:
I was an ATT postpaid mobile customer for the better part of a decade, and now a prepaid customer for over 3 years. Never have I had such failure in receiving a reasonable resolution to an issue as I have in this instance.
On September 21st, I purchased, for full retail price, an iPhone Xs from Best Buy. Approximately 4 hours later, I left the US and returned to Grand Cayman where I am currently staying with my fiancee. Upon arrival to Grand Cayman on the morning of September 22nd, I attempted to insert my FLOW sim card and was given a message that my sim was invalid... I have never received this message before so I was completely unaware of what the issue could be... as it turns out, I wasn't the only one! Speaking with my first two ATT representatives, they also were completely unfamiliar with why a phone I paid full retail for would be locked.
After approximately 8 hours of my own research combined with calls to ATT, Apple, and the Best Buy store I purchased the phone from, I was finally able to deduce that the phone was locked to ATT because the first sim card I inserted into the phone was my ATT prepaid sim... When I found this out I was in complete Shock... Why would a phone that I paid FULL retail for, received no benefit from ATT for, and at NO POINT acknowledging a contractual obligation of 6 months active on the network, be locked??? Apparently, this is how things are done... Consumers are locked into 6 month contracts without being made aware that will happen... ATT just "hopes(??)" that a sales agent at a reseller will verbally tell the customer they are effectively signed a contract?? That seems ludicrous to me.
After a further 3 calls, and 3 separate denials to unlock the device... a supervisor has emailed the "back office"... I was told approximately 40 hours ago that I would receive a response in 24 hours.
I am asking for that response... and that response should be my phone being unlocked for me to use as I see fit... I would appreciate any help in the matter you can offer.
In closing there are 4 key points to this issue:
1- The store representative at no point made me aware of this issue... it would have been MUCH easier for me to simply NOT BUY the phone than to have spent the last now 8 days dealing with my $1300 unusable phone.
2- I am now locked into a contract I didnt accept and more importantly was NEVER given the chance to accept or deny!
3- The 3 denial emails all came with the title "Subsidy Device Unlock Request" THE PHONE WAS NOT SUBSIDIZED... I received NO benefit from ATT for this device... I paid for my service and paid for the phone at full retail... the very implication of the email is that I received a benefit when I purchased the device... I did not
4- the email ALSO states that I must be an ATT prepaid customer for 6 months... I've been a customer for over 3 years... the denial does NOT state I must use THIS device for 6 months
I truly hope this can be resolved... and more importantly not a single other person buying a phone in the United States should EVER be locked to a contract without their knowledge