Promotion FNB Virtual Credit earns clients R2 / litre is false advertising

FNB have advertised recieve R2 / litre be using virtual credit card at engin petrol stations. Virtual Credit card works at all other retailers except for Engen. Transactions occurred: 23 Dec and 27 Dec to the value of R1700. This is escalated every day for over 2 weeks, FNB and eBucks cannot assist. Reference numbers: RM***, ***NF