De*****ing clients

I went to autopage and requested a cancellation fee and I was give the amount and told to pay within seven days. I paid and called on to cancel the contract it was confirmed that it was cancelled. Today I got an invoice to pay for the next month, I called the customer service and I was told it was reversed as I can not afford. I don't understand that and I have done what was requested. I cancelled it so that I can be debt free not to be de*****ed *******.