Cancel my Rain internet

I cancelled my 1 sim during September to upgrade to 4G unlimited internet. They sent me a new modem and new sim, end of October I got this account with old sim included. I tried to cancel 4G but nobody seems to bother to cancel this, I will pay the usage of 4G during October but they don't want to cancel??? The account keeping increase every single day. When I took out Rain they advised I can cancel any time, this was a total lie! Please cancel my internet I will pay the 4G but don't want it to carry on during November due to Personal issues.