Hollard don't respond to complaints

I've been trying for months to get hold of someone at Hollard to cancel the insurance product I have with Hollard. The problem is, I don't know what the product is! I signed up many years ago and was never sent any documentation. Nobody at the call centres can help or find me on the system, yet you're happy to still bill me every month because of course, you still have my bank details.

I've emailed to complaints address multiple times, all are ignored. I've now resorted to putting a stop order on the debit, as well as now closing my bank account and switching to a new bank to get away from you *******. Will someone please actually make some sort of effort to contact me so I can cancel this product and stop fighting about it?