Product: Credit card or prepaid card

This is the letter we sent to XXXX with our payment. I am including, after this letter, another part of this complaint that happened in the last several days. XX/XX/XXXX TO WHO IT MAY CONCERN : WE ARE VERY UNHAPPY CUSTOMER. TODAY ( XX/XX/XXXX ) I WAS ABOUT TO PAY OUR XXXX XXXX  BILL AND NOTICED WE HAD BEEN CHARGED AN INTEREST CHARGE OF {$8.00}. ON OUR BILL DUE XX/XX/XXXX, ( CLOSING DATE WASXX/XX/XXXX ) OUR PREVIOUS BILL ( DUEXX/XX/XXXX ) HAD BEEN PAID IN FULL TO THE DATE ON MY PREVIOUS STATEMENT, ( XX/XX/XXXX ) IN THE AMOUNT OF {$830.00}. ( EVEN THOUGH THIS AMOUNT INCLUDED A LATE FEE AND FINANCE/INTEREST CHARGE THAT HAD ULTIMATELY BEEN WAIVED BY XXXX XXXX. ( In a phone conversation on XX/XX/XXXX) THE EXPLANATION I RECEIVED FROM YOUR CUSTOMER SERVICE REPRESENTATIVE, XXXX AND SUBSEQUENTLY ALSO FROM XXXX WAS THAT ANY CHARGES FROM THE CLOSING DATE UNTIL MY PAYMENT IS RECEIVED ( by XXXX ) IS CHARGED INTEREST ON MY NEXT BILL EVEN THOUGH WE PAY OUR BILLS IN FULL EVERY MONTH. SO WE WERE CHARGED AN INTEREST FEE ON A BALANCE OF ' {$650.00} ', WHICH WE MORE THAN PAID IN FULL AND ON TIME. AND THAT EVERY FUTURE MONTH WE WOULD NEED TO CALL OR GO ON LINE TO SEE WHAT OTHER CHARGES WERE POSTED SO THAT WE WOULD PAY ALL AMOUNTS POSTED TO OUR ACCOUNT, ( after the bill closing date ) NOT JUST WHAT WAS ON OUR STATEMENT. THE WORDING I WAS DIRECTED TO ON OUR BILL DID NOT SEEM TO EXPLAIN WHAT I WAS TOLD BY YOUR REPRESENTATIVES AS STATED ABOVE. IT WOULD HAVE BEEN VERY FAR FETCHED FOR ME TO COME TO THE CONCULSION AS PRESENTED BY YOUR REPRESENTATIVES. WE ARE VERY CONSCIENTIOUS CONSUMERS AND PAY OUR CREDIT CARD BILLS ON TIME AND IN FULL TO AVOID INTEREST CHARGES AND LATE FEES. DUE TO YOUR UNSCRUPULOUS CHANGE IN POLICY AND RULES. WE WILL NOT USE THIS CREDIT CARD. WE WILL ALSO MAKE IT KNOWN TO ANYONE WHO MIGHT BE INTERESTED THAT XXXX XXXX  AND CREDIT CARD COMPANY ARE NOT A VERY CUSTOMER FRIENDLY BUSINESS ETC. WE WILL ALSO CONTACT THE CONSUMER AGENCY NECESSARY TO REPORT THIS UNFAIR PRACTICE. WE HAVE ENCLOSED OUR FINAL PAYMENT OF {$330.00} WHICH COVERS OUR LAST PURCHASE OF {$61.00} ON XX/XX/XXXX. ( 8 DAYS AFTER OUR BILL CLOSING DATE ) WE WILL NOT PAY THE {$8.00} FINANCE/INTEREST CHARGE! Signed Today, XX/XX/XXXX I called XXXX to see if our payment was received and posted. After listening to the automated recording of my account information and realizing that my payment was still outstanding I spoke to a customer service representative.. I told her I sent the payment and letter to the address on the back of the bill that specifically directed this action. She said that there was a PO box at this address that is checked several times a day. The address used was NOT a PO Box . I asked to speak with a manager. The MANAGER could n't even find the info I referred to on the back of the bill statement and then said that this address was meant for " overnight ' delivery of payments ' that usually come from a bank or are sent by overnight mail '' There was not one thing in the statement read that referred to her statement. I have included the back of the billing statement and highlighted it for your perusal. Also highlighted the statement on the same page that states there 'policy ' for interest charges and fees. Which also does not state what they said. In addition I am including a page with the newly added notice of record changes. I can not for the life of me understand how they can put a statement on the back of the bill saying where to send a payment that says " paid in full ' '' etc. and not process this payment. ( I checked with our credit union to see if the check was presented and it was not ) Also these to representatives stated that " I should stop payment on my check '' ( which we would have to pay for! ) PS my CC # is on the attached statements.