Bad service at Avon Justine

I have called Avon Justine requesting my paid up letter I even came here after I came here they called me it was the 1st of October when I wrote here, they promised that they will sort out the issue and send me the paid up letter.

Now I am stuck because the Debt review company says I must get a letter from Justine myself as I have paid them, before they can remove the red flag on my credit report. I am not happy at all with how they are handling the issue?