Who diagnosed a bad coil? That'd be a rare part to fail and obviously didn't fix your car.
Is or was the engine missing? If not, it can't be a bad coil.

My dealership isn't opened weekends either but you should have it diagnosed by a dealership that has a Vadis PC if not done before. They can also print the diagnostic fault codes, now required for warranty so you'll be able to see what the codes are this time.

If the engine isn't missing, running rough and has normal driveabilty, it's probably not a major thing to worry about but you should still have it properly diagnosed by a dealer next week.