Cancelled Contract- still being billed

I cancelled my voice and data contract with more than a month's notice and I am still being double billed by Autopage. I have contacted the call centre on numerous occasions via phone and email requesting a statement, but have still not received one. This month I was double billed for 3 x amounts by Autopage. The customer service is existent and I have yet to receive a response regarding the numerous queries I have sent them.