Paid up letter

I had received a settlement amount from Nimble for my Standard bank account. The amount was paid within 2 months but what Nimble had told me was that they haven't received the 1st payment which was done on November 2019, the only payment which they had received was for December.

I sent proof of payment so many times no one assisted or responsed after I had send the emails so many times.

Standard bank is asking for a settlement letter,sms or email which I was sent for the discount in 2019 so they could give me a paid up letter. Nimble hasn't been able to be helpful up until today the have my money but what I am asking for help could not be provided. Will you'll give me my money back which I had paid.

The only thing which I need is the amount of the settlement which I was given as proof.