Most petrol stations nowadays do not accept Visa Debit or Credit cards. Only the Shell (soon to be gone) ones accept.

Telling you the machine is not working is a polite way of telling you they don't accept cards.

Or could be something totally different, like the back end being down but that should affect like everyone from supermarkets to restaurants and bars that accept cards. By the way lawyers, is accepting credit cards in a bars selling alcohol on credit?