Unable to cancel sim card

Trying to cancel Rain simcard is a disaster. Clicking cancel sim on the website brings up a pop up to inform you that you won't be able to re-activate once cancelled. You confirm by clicking Yes. Only thing is if you click Yes, it goes back to the previous screen and nothing happens. I tried since last week on different browsers, different internet providers, pc, laptop, phone. Finally I contacted support to ask them to cancel the sim. Got a reference number and never heard from them again. Am I going to be charged pro-rata for August even though I've been trying to cancel since last week already? Please someone from Rain, cancel my sim card immediately.