MTN Contract Cancelled and still debited while contract cancelled

The worse ever cell phone company. They send you statements and invoices while you cancelled your contract with them. Cancelled 22 Aug they sent me a statement on 16 Sept with full amount outstanding, debited the full amount up until 12 Oct but my last date of contract is 22 Sept. This company is the most ********* company ever. You pay upfront for your data allocated but they just decide to debit your account for the next month also after the router is disconnected also, you pay for data that you did not get. They are and will always be a very dishonest company and they wonder why people leave to other service providers.