Woolworths

I have completed my term of DC a couple of months back, yet according to Woolworths, my account is in arrears. I have been sent a paid up letter proving that the account has been settled. I do not understand why Woolworths is not updating the system as it is affecting my credit score. I have called and emailed countless times and am yet it get a response from them. THIS HAS BEEN VERY FRUSTRATING!!!!!!!!!!