Had a similar experience when I left my previous ISP. I didn’t even have a choice to keep the service as I was moving. Upgrading the service was an easy click, but cancelling consisted of reading through their help pages to find a number to call, which of course was only open a few hours per week. It explicitly said that this was the only way to cancel.
Instead I simply sent them an email insisting that I wanted to cancel, and that I refused to talk to them on the phone to do it. They replied with a “great offer” to reduce the price. In my reply I simply insisted on cancelling. I didn’t hear from them again, except for a confirmation by post a while later that the service had been cancelled.
Of course, this is much more effort than it should be, especially an emotional effort because being treated like this is very upsetting. But it might be worth trying.
Instead I simply sent them an email insisting that I wanted to cancel, and that I refused to talk to them on the phone to do it. They replied with a “great offer” to reduce the price. In my reply I simply insisted on cancelling. I didn’t hear from them again, except for a confirmation by post a while later that the service had been cancelled.
Of course, this is much more effort than it should be, especially an emotional effort because being treated like this is very upsetting. But it might be worth trying.