Some debit cards will not work at self service payment terminals, such as petrol stations, as they use a process known as 'offline transactions'.
An offline transaction is made at a terminal with no network connection, so no payment is sent for authorisation. Without this step your available funds are never considered as part of the process, and some debit cards will not work.
For risk purposes we will only allow a card that can be used in this way to be issued to customers who have a credit rating suited to this kind of facility.