Unauthorised debit orders

This is the most poor service I have ever received in my life. Basic bloods and xrays not paid can never get a hold of anyone to assist with claims. Have cancelled this plan 2 years back and they keep on deducting a premium from my bank account. My bank cancelled the debit order they keep on changing the deduction code. In other words they are *****ing my money and reversing the debit order effects my credit rating. This is unacceptable if you don't contact me in the next 24 hours it leaves me with no other choice then to take this further. I can't get a hold of no one phone calls are not answered.