Supersonic not responding to cancelation requests

Our fibre speed has been very poor lately - supposed to be 50mbs up and down, but we get speeds between 0.8 and 3mbs on some days. There has also been many outages where there is no connectivity for hours at a time and I work from home so can't afford to be with internet access. We decided to cancel our contract and I sent an email to the designated email address on 8 February. I followed up on 13 and 14 Feb, no response. Not even a reply email with a reference number. Supersonic requires a 1 calendar month notice, which means if they responded when I sent the initial request, we would have been able to move to a new ISP at the start of Apeil. Now we're in March already, which pushes that out by another month. This is unacceptable! Their lack of service on all fronts means we are paying for a service we're not receiving, but they also won't let us cancel and release the line so we can move to another ISP. Surely this kind of underhanded stalling tactic is *******? Has anyone else experienced the same thing with them?