MTN doesn't want to issue my paid up letter.

I called MTN requesting my paid up letter, they told me to call NuDebt. NuDebt is not responding to WhatsApp messages and they told me i will get my letter on the 11 October, but still nothing. MTN can i please get my paid up letter, you reactivate my account after telling you in writing that you shouldn't. now i have paid, you making it difficult for me to get my letter.