Netstar poor service

I cancelled my Netstar subscription on 24 January 2025 already. I have been harassed by them for payment, though I gave them 30 days notice as they required. Every agent that calls and the collection agency they have appointed to harass me, has been given the reference number I was given when I gave them the 30 days notice to cancel... it makes no difference and the matter has not been resolved. I have sent numerous e-mails on their request with the refence number... no resolution. In fact, Netstar, before I cancelled, deducted the monthly premium by way of debit order on the last day of the month; now, since cancelling, the allow a deduction on the 25th of each month off my account. I have to reverse the payment each time and I carry the bank charges for this. They were, in addition, suppose to come and remove the tracking device from my vehicle on the anniversary of the 30-day period... not a soul has been here and it already June! Never used to get invoices (via e-mail or post) from them. Since cancelling they send an invoice each month. Laughable to say the least. They never had to track my vehicle, thankfully so they made pure profit off me. Can they at least now get their house in order; cancel the subscription and stop taking money from me via, what seems to be a newly established debit order. Oh and come and remove your device please.