Denied refund

I recently made a payment for my contract on their Self service Appfor May payment and I was also debited which counts to 2 payments in a month I emailed them and made a numbers calls also to ask for a refund for one of the payments I have emailed them all the necessary documentation they asked for and even answered their verification question but still no refund and is day 8 today I have received the worst service from their customer service and no feedback back received whenever I ask for a feedback regarding my refund they ask for a document every day