Mix telematrix - unfair practice and poor capacity

I had a Toyota land cruiser covered by this tracking company I sold the Cruiser on 12 March and phoned Mix-telematics on 13 March and wrote an email to cancel the policy. Despite incorrect correspondence from this company regarding the cancellation date as well as numerous telecommunications they still charged me the whole of April despite having cancelled the policy on 13 March telling me that i had to cancel before 07 March so as not to be charged for April. This to me is extremely unfair business practice and not in line with other insurers - basically to be charging a client for no cover for over one and a half months. Outsurance and Discovery for example cancel your policy payment with immediate effect if you choose to cancel a product Coupled with the evidently poor capacity to even communicate factual data as well as poor capacity to understand and even give coherent advice (numerous calls) - i would not advise anyone to use this tracking company - a total joke!!