Cancellation dispute

We cancelled our Mix Telematics tracker unit in November 2019, the settlement amount due was R215.22 which we paid immediately. Now 19 months later we realize that they have been collecting their monthly debit orders non stop. When querying this they claim that the settlement was R1215.22!!!!! They are flat out refusing to repay the 19 months and keep on saying for almost 2 weeks now that the are looking for the settlement email sent to us... This is extremely frustrating as they take days to respond to emails.