Gave a month notice to cancel my DSTV and they still deducted it

On the 1st of may I called DSTV business to cancel my DSTV for my business. They told me I should mail them and it would be done. So I did it. But with regards to this they still deducted my dstv from my account end of May. So I called again and asked for a refund. they told me I should have got a case number. I told the I mailed them and have proof it was delivered but did not receive a case number. They then told me I should have followed up and because I did not get one it is my fault. I have not used my DSTV in more than 2 months as my business is closed. And the guy that told me I should mail never told me I should follow up for a case number. So money was deducted which is unfair. they never did their job to cancel my DSTV as they are working from home and doing their work when they feel like it. They don't want to refund me. This is unacceptable and against the consumer law and if someone dont contact me from DSTV and refund me I will take it further with the appropriate authorities. so give me the recordings of that discussion beginning of may or legal actions wil be taken. Or make it easy and refund me