I am working for a company that owned a postage meter. We were unsatisfied with the charges we were getting per month so we decided to end the service. My boss called the company about sending them back their meter and how to end their service. They said just pay the past amount due and current amount due and so we sent them in checks with Paid in full, close down accounts. So the next month they send us a bill and we figure it was a fluke and throw it away. The next month we get another bill and a call from them stating we owe them money. We explained to them we didn't own the meter anymore and were paid in full. They have sent us many invoices with finance charges on it. I called today and told them we were told the amount we owed, paid it, with paid in full in the memo and they told us we did not pay the full amount. I then told her my boss personally was told the amount and I wrote it down and made out the checks which I sent out that day. We have a bank statement showing they cashed the checks. Who is right?