So I thought I'd have one last ditch attempt at contacting support on client zone with the abovementioned issue, maybe they improved the support or something.
Here's their reply, took them 3 hours and 48 minutes to reply with this:
Thanks a lot for making the decision easier - account cancelled already, now just to wait out the month with this horrendous drivel of an internet service.
Sorry to hear that you have cancelled. We are committed to keep trying to resolve this with you. But if you have decided it's better to move away, I respect your decision.
Either way, you are always welcome to PM me if you'd like to discuss further. Perhaps we can still make your performance as good as possible for the remainder of the month