I just calles Sear Auto to schedule an appointment-my wife took her car there, and they would up doing a lot of stuff that I didn’t like:
-they changes the spark plugs (they were changes 26,000 miles ago, good for 100,000 miles
-they flushed the engine coolant (it was done last year)
-they did a front end alignment (was done in March this year)
Anyway, last week (5 days after the service), the exhaust system developed a leak-my mechanic found the pipe-muffler joint was broken ($60.00 to fix)
-the toe-in was set incorrectly (off specification)
-today the check engine light went on-code indicates a plug misfire (my mechanic thinks the plugs were gapped incorrectly
I’m going back to sears-is this just coincidence, or did they screw up?
Well, I hate to disparage anyone so I asked my husband to do it. 
He says, nope, no coincidence. They need to fix it.
I’m in the ‘no coincidence’ camp. They definitely need to fix what they messed up, and if they mention other things that are not a portion of what they directly worked on, I’d find somewhere else to go to get THAT fixed.
Are spark plugs even supposed to have their gaps altered anymore?
But yeah, Sears needs to get their filthy hands on your car again until they get it right.
Regular old spark plugs are supposed to come pre gapped, but in my experience they are usually off. Newer plugs with electrodes made of platinum and other fancy stuff should never be adjusted.
ETA: OP said the plugs were supposed to be good for 100k miles, that implies they are platinum plugs and shouldn’t be gapped.
Its a mess-up. They need to make it right. On the other stuff that they sold you… well that’s done now. But you might want to consider all of this when deciding whether you want to use that store in the future.
Not.
Sorry to say this, but your first mistake was sending your wife. After seeing what car repair people have convinced Laura of, I never send her in to get the car fixed.
The above isn’t a comment about your wife, mine, or women in general, but about how car repair places use fear to convince women to pay for unnecessary repairs. “You won’t want to be riding with your child in the back seat w/o the front end being aligned, nosiree!”
Coincidence? It’s more like a goddamn conspiracy.
Not uncommon to bump a sparl plug while installing changing the gap. I would ask for full refund on alignment unless they can show proff it needed it. They pull this crap all the time. If you car was out of alignment your tires would show thew wear. If they were showing wear did they do it wrong last time?