Cancellation of contract

So again I had to to call Rain to cancel for a third time. I used Hellopeter the first time round complaining about the cancellation and Rains response was when do I want it cancelled. I told them on the 22nd of March and only to find out it was still active. Called their customer service which couldn't explain to me why it was not done. I unplugged this router the 23rd and was using my new service provider. So Why am I billed the full amount month end when I clearly stated that I'm not using their service rrom the 22nd March. This is extremely bad service, paying for a service I not not use. Very unprofessional company.