Charge without notification??

Using a petrol/garage card for years, Standard bank decide to put a levy of R5.50 on every transaction without informing us the customer. Went to the bank to equiry about it, not a single person knew about it. Lodge a complain on the 12 January, ref ***. Promise they will call me back, but no call up to date. So I went to the bank again this morning. After phoning they were informed that there is a levy since 1 January. without informing the customer??? Using the card somedays three times a day, we feel that is not fare.