Struggle to cancel

Sonic Telecoms service has gone from fare to worse, I am struggling now to cancel my account, wrote a email the 3rd of this month but no one is replying, my internet is always being capped and I don't even download anything, their packages are more expensive where I stay probably because there is no fiber yet, just a warning to anyone wanting to take out their internet find out how it works because they change their internet usage without you knowing and throttle you without you knowing why, I recently checked my internet speed and it's not even the speed I took out its less, please can someone get in contact with me as my contract runs out by the end of this month and it's required to give a 30 before hand cancel request, I want my internet canceled, thank you in advance .