Refund+Cancellation

I recived a call from getbucks advising me they are offering me a an insurance/get legal/getsure the guy promised to send me a copy of the contract which he never did, i requested to cancel the policy till today, i need this policy to be canceled asap, i was told the premium is 115 but sometimes i see a debit for 18.00 /25.00 and sometimes i dont even funds on my account and the bank charges me 115.00 for a failed debit order?i need them to calculate these failed 18.00/25.00 and multiply by 115.00 and refund back to me.<br>