Electrical problems with Fiesta Encore

When I was driving yesterday evening, the indictors on dashboad flashing suddenly and the needles of the speedmeter shanking, the wipers swing I can not stop! the worst thing is the front light and side indictors all out of control! I have to pull off, and call RAC for recure! However, when RAC came, everything back to normal!!! Anyone know what the problem is? Many thanks!