Mix Telematics, stop taking my money

I changed insurances to Discovery, and sent an email on June 16 requesting the cancellation of my account, reference ***7. Someone called me and promised that it will be cancelled, so I thought the July debit will be the notice period. When the August debit went off, I sent emails on 01/09/2021 ( ref ***2 and ***3) with no response. I then sent emails on 06/09/2021 (ref ***0, ***2 and ***3). Still no word, I have now resorted to reversing the debit orders. Debit order went off again, and again i have sent emails (ref ***5, ***6, ***8 and ***9) I have been a loyal customer for years and just don't need the service anymore but it is proving impossible to cancel.