Lost my number

Changed my number and had no idea! They refuse to even try and get1 my acct fixed. They say they have no record of my old number. I said then how do I have service on this phone!!!! This is new device t1hT was a t1ivated for first time. Few weeks ago with diff phone number. I can prove this number was not my number before .. they run me around. All my accts could be compromised. All my Dr updates are texts my savings app are with text and number all the accts that verify by sending code to my number...how can they do this