A credit card payment processing company agent approached my business and offered to try out their service for free for a month as a trial. However, I decided not to use it after this one month trial, and request to cancel. Now they have already charged $840 as cancellation fee and PoS deprecation fee. Since there was no contract, I don't agree to pay these fees. Do I really have to pay them?
A contract need not be written to be valid and enforceable. However, if there is no written contract, then in a dispute the burden of proving (via a preponderance of evidence) a contractual obligation falls on the party asserting it. In the scenario you describe it sounds like that would be impossible for the processing company.