Cancellation conviniently ignored

I have a long-standing issue with this network regarding a February payment that they have failed to link to my account, and despite sending numerous proofs of payment, they couldn't assist me ( the billing team is totally useless and has not once returned to me after sending the POP). As a result, I requested Rain to cancel my subscription around the end of April, towards the beginning of May. I was clearly ignored when I cancelled. Now they are billing me R3749 for services I have not consumed, and have been disconnected under the assumption of the cancellation I requested. I have been using another ISP for months and not interested in your services