Unable to terminate my Cell-C data contract

I am very disappointed with Cell-C because , I am finding it so difficult to cancel my data contract with them. My contract ended on the 30th of September and I have been trying to call them so they can terminate the contract, so that it doesnt turn into a month to month contract. I have called them, went to the Dainfern square store and the fourways mall store. Both stores were unable to terminate the contract, they were both also unable to reach the retentions department. May I please request help to get the Cell-C retentions to terminate my contract. To cell-C management your 084135 number is useless, your people do not answer. Please build capacity because at the current moment, its clearly not working