Tell joy sucks

I've been trying now to get these people to sort there system out because every month it says I'm in arrears and I have been paying every month. I've also sent emails and never got a response. I've called in a couple of times and every person I spoke to said they would get it sorted and send me a email the same day.im still waiting and now I can't do anything because my credit rating is bad due to them saying I'm in arrears