Reading your post, I gather that you bought a new wheel and you suspect the shop installed a single speed freewheel backward.
If that's correct it's an easy fix. Turning the sprocket to the left will unscrew it. Wrap a rag or belt around it for grip and just spin it off, then flip it over and install it correctly. If it's on too tight put the wheel in the bike with the chain on normally. Tighten and backpedal with the brakes on and it'll loosen, then you can finish by hand.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.