So I moved out of a flat in July and my energy account was closed immediately afterwards. However, my supplier British Gas sent me additional bills for the period after my tenancy has ended and demanded me to pay since the account is still under my name (Although i have closed it). British Gas has urged me to contact the landlord to create account with British Gas so they can bare the cost; however I tried contacting my previous flat agency and they just refuse to cooperate or showing any tendency to bare the bills that was incurred after my tenancy ended. The current tenant of the address did not move in when bills accumulated and they have switched landlord agency, as well as energy supplier after the moving. This means the property was vacant, and it would 100% be the landlords liability, but I'm struggling to take actions as my previous landlord refuse to respond; any advice?