Telkom incorrectly charging for a service that was cancelled

My 24 month contract for a LTE service expired in February 2018. I timeously contacted Telkom and was emailed the cancellation documents to complete and email back to the consultant. I did that and despite numerous follow ups, received no confirmation and even re- submitted to another consultant. Telkom has now listed me on credit bureau for outstanding balance and is negatively affecting my home loan application