Were you still in a 18 month minimum term period with VM when you cancelled or had you completed that and were 'out of contract'?
Normal process is you have to give VM 30 days notice to cancel. If you are in a minimum term period you can (almost certainly will) be charged early disconnection fees.
If you are not sure if you have cancelled, or not, you are right to query it as VM is fairly relentless in chasing down debts if it thinks it is owed money.
You are unlikely to receive a reply from the VM forum team here in ‘Community Natter’. A VIP or moderator might move your topic to a better forum, such as ‘Managing Your Account – Cable’ to get a VM reply.