SIM card cancellation problem

I have no words for this company and how costumers are being treated. I have asked to cancel my SIM card and I am not getting the assistance I need. I asked them to cancel in March now I'm told that I have to pay the amount of R612 which i do not understand how it even got to R609 whereas ii was in the R479 product. It is a month to month contract and now I am told that I am on a postpaid product which according to my understanding they have to get my permission to credit score to qualify for a postpaid package. No one told me of a postpaid product. Now that I've been wanting to cancel suddenly I owe them. I have been asking to be called but an agent named Kamogelo Seoposengwe is refusing to let their manager to call me as I have requested to be called by a manager since no agent has called me since I requested to be called since beginning of March 2021. I advised them to pull their call recordings as I never agreed to a postpaid product. Up until now nothing. This is the second time I even requested for them to cancel. They told me they removed the cancellation function on their website until I pay. There is not even a number to call. How do you run a telecommunications company yet there is no call centre. What nonsense it this.