Do not buy on credit at Lewis

I bought a couch on credit at lewis stores. The coach had ugly marks on it when it arrived one week later as promised. A debit order was set up on the day that we signed for the couch. It goes of every month, but every month they call me and tell me I am not paying when I sent them the bank statements they do not reply me and if it does get sorted out the next month they call me again. This is making my credit score very bad and I am paying my account every single month on the 26th.