That's an easy relay to find, most any autoparts store will have a compatible one. But that's not your problem. Those relays can handle more voltage than your car will.
I suspect you have an issue with the ignition switch or the wiring for that accessory line. The relay isn't getting triggered. Since you're on the road, easy fix would be to wire in a switch to power the signal leg of the relay. Otherwise I'd be trying to splice into the ignition "run" circuit.
