MTN continues to draw debit orders after a data plan was cancelled -cleverly changing the amount

MTN is very clever. I cancelled a data plan in May 2020 that ended on 5 June 2020. Last debit order to go off was 25 May 2020. Consultant tells me its cancelled but that MTN's "systems sometimes continues to draw another debit order". I said I trust that wont happen. And guess what. They draw another debit order on 25 June 2020 which I had reversed with my Bank. Thought they learnt. On 25 July MTN drew another debit order, but this time cleverly changing the amount slightly and the second part of the main reference number. As a 26 year customer I am shocked beyond words that they would do this. Its ******* and bears no integrity. I have sent a complaint asking that someone contacts me. NOTHING. Go onto the live chat. NOTHING. Call the customer service, hold on for FOREVER with no agent answering. Maybe the ombudsman can help me.