Truworth poor service

I july went to pay my account at truworths , I had an account before and it was no longer using it, nstead of putting the money on a current account the cashier have put the money on a previous that has zero balance, now on my credit status It shows I'm behind with 1 installment and in was rejected on something that I wanted to take on credit due to that I'm so disappointed and my credit score has drastically decreased