I can't cancel my contracts

It's impossible to cancel my contracts. I just failed the security check 5 minutes after passing the same security check with another agent (same questions, same answers, but I pass one and fail one). I can't go to branch to cancel - I can only cancel via the call centre but I fail the security check. So now what am I supposed to do?

I've had a couple of bad experiences with CELL C in the last 8 months, and today is just the cherry on top.