Bad Service

For the last 2 weeks, I have had daily calls from Truworths regarding my installment, I have made all the payments as I am used to and sent them the proof of payments several times, but still get phone calls daily to state that my account is not paid, and due to their lack of work my name is now bad on my credit profile for late payments. Is there some one at Truworths that knows how to do their work and get this resolved please.