Dispute charges

I need to dispite and ask for my account get cleared since my account was never hooked up at my new house.  I'm a 20 plus year customer of DTV and sad that this has happened to me....my account number is xxxxxxxx (or at least was my account number)...Please advise on my next steps to help me get my account to zero and not at 744.50....My account was never hooked up.  In addtion to that I returned all the equiptment on 9/22/22.