Duplicate card transaction not refunded

I have been requesting from FNB to refund a duplicate card transaction since the 8 January 2016. I have confirmation and proof from the store they only received 1 amount and that the funds are sitting in a suspense account and waiting for instruction from FNB. I have sent all relevant paperwork to them about 7 times and still have not had 1 phone call or even email from them. Called them to find out that nothing has been logged. Banks are ******* as it is and now they blatantly ***** money.