Trouble using your card: Credit card

I received my new Citibank credit card and attempted to use it for the first time while traveling to another state to look for an apartment because I was relocating. Before making any real purchases, I made a $1.00 test transaction at a gas station to confirm that the card had been activated. The transaction was approved, but Citibank immediately blocked my card for suspected fraud. I contacted Citibank multiple times and explained that I had moved and no longer had access to the mailing address on file. I asked them to verify my identity using another reasonable method, update my mailing address, and restore access to my card. Instead, they insisted on sending a verification code only by regular mail to my previous address, which I can not access. I also asked to close the account if they were unwilling to unblock the card, but they refused to process the closure because I could not provide the code mailed to my old address. As a result, I am unable to use my credit card, unable to complete the identity verification process, and unable even to close my own account. Citibank has not provided any reasonable alternative to resolve this situation despite my repeated attempts to work with them.