Unnecessary Delay In Refund - Poor Customer Services

In June 2020 I had requested cancellation of my ADSL contract (which was ending) with Telkom following the their instructions of 30 days notice. I was informed that I had to wait for 2 months of billing before eveything would be finalised. After receiving the 2nd month bill, I requested the amount owing to us as refund. However I received a call from a Telkom consultant on 15 Sep 2020 informing me that I now have to wait for another month of billing as the sim card somehow was not cancelled. Telkom is not a choice as service provider because their customer services are really poor. Why can't Telkom escalate the matter & do the refund asap instead of making the client wait another month for billing? Am I as the customer going to accrue interest on the outstanding money due to me for this additional month?

Can senior personnel of Telkom kindly intervene & have my money refunded asap please.