Over promise and Under Deliver

Through in petrol at BP Tygervalley end of March 2015. Paid with FNB cheque card and then noted with my month end statement that the amount was double deducted for fuel. Queried it with BP Tygervalley in April and was told that it was an error from their bank Standard bank. Was told the money will be back in my account within 48 hours. Its now 3 weeks and I am still waiting for the money to be refunded. How important are we as so called clients to FNB and Standard Bank. FNB states how can we help you! They still have not assisted with the query of refund monies. Pathetic service from BP Tygervalley and FNB banks.