Very unhappy customer

I bought a bedding cash on black Friday including delivery fee . I am not owing them anything . I 've moved to another flat on the 1st of December 2020 .Home choice requested a new address to be updated last week Friday and I have updated my new address online and also emailed them but now they are requesting letter from municipality as a proof . I've told them I don't have it , I have not received any letters on this address because I just moved in . Now they are playing hide & sick Please assist