I bet no one can help but thought it worth a try.
I bought an Iphone 12 when in the US and was told it was not locked and I would be able to use in the UK. This worked well but for a few years but I reset my phone to factory settings and now it will not accept the SIM i was using. On investigation it appears to be locked by a reseller flex policy. I was advised to contact the phone company to get them to unlock ( which I believe to be Verizon) it but it is impossible to find an email contact and I can't log in to an account as I don't have the original phone number on an account etc etc. Does anyone have any ideas before I have to bin a perfectly good phone? Thanks.