Absolutely useless accounts department

They have no clue on how to run my Edgars account. Interest charged monthly on an interest free account. I only buy from Edgars and then get told it is because I am using the card at a subsidiary store…what ******* and lies. Then I get told I paid late…payment is due on the first of every month and I pay days before the due date. So more lies. I get told your account is moved to interest free and still I get Cii argued interest. The latest lie is that stores do not have the ability to know I have an interest free account so even though on the keypad, I choose 6 month plan, it is futile since the store has no ability to mark it as a 6 month account. So why the heck do they have the option? I get charged a principal debt adjustment fee and no one can explain what this is for. Absolutely useless and a shambles.