Pathetic service from cellc

I just received a threatening call from a lady from the communication department from cellc acting concerned about my review to my surprise she is ****y and rude.the amount that I now owe cellc has changed from R515.00 to R2100 and the sad part the contract ended in July I submitted my cancelation on July the reference number received from celllc stated that the contract will end on the 26 of August the number was no longer in use since August to my surprise now the contract was never canceled I must now pay cellc R2100 which is the new amount given today. It started with R515.15 then R960.00 then R1900.00 now we are R2100.00 yet I don't receive statements nor messages about an outstanding balance from them.i requested financial statement with regards to the account I was told they cannot provide that the reference number I got from cellc is now disregarded I now wonder how did I get the reference because cellc emailed me the reference.its going to be a very long battle with regards to this but I will not pay for something I did not use