Paid up letter and Bureau Dispute!

I settled my account on the 3 December 2019, I was promised a paid up letter after 14 working days! To date, I haven’t received anything and it’s showing as unpaid on my bureau which affects my credit score. I’ve been to Telkom on many occasions with no luck! I can’t get this removed from my bureau without a letter from Telkom stating that I’ve paid up my account.