Disappointed and false info provided to my credit

Very angry at the moment with Wonga, they have issued a non-payment to the credit bureau and clear score which reflects that I missed a payment which is not true. My account is up to date, changed banks contacted them and was advised by the consultant due to active account she is not able to update and the I must make EFT payment. I did this immediately on pay day, only to have them phone me two days later. I told the collections department exactly what I was told by the consultant, which I then sent them the proof of payment. Now they have went and issued a non-payment, which is a lie and false as payment was made and I am up to date and not in any arrears, because of their system and I that did what was told by their offices, this has now affected my credit score. It is unacceptable and must be rectified, as it is untrue what they are insinuating of me. December is my last instalment, thank goodness I am done with them.....