Mix Telematics system failure customer problem

If I could warn the anyone against Beame / Mix Telematics please be careful when cancel these units is a nightmare, I sent my 1st request for cancelation in November 2021, 2nd request 1 December 2021, received a mail from them acknowledging the cancellation and confirming that the contract has been terminated with immediate on 17 December 2022 after numerous calls to the call center, now I am being sent mails for arrears and when I called to sort out I am told by accounts I must sort with cancelation department as they confirmed the immediate cancellation, and if I do not get this sorted with them I will have to pay the arrears amount as the system says I owe them, how is it that I have to be penalized for their system/staff error.