The weight difference alone should have been a clue to the difference in size. I advise you to follow out what I'm going to say next...Go to the first bike shop, raise hell, get the right wheelset, demand that they do it, compare the hubs rims and weight to be sure you are getting a wheelSET. Bring your bike along with you to check fitting while at the store, install the wheels in the parking lot if you have to. Then take it home and call the second shop and tell about the wheelset that you purchased and varify that you got a matching set.

If you let a shop get away with hasseling you and taking your money for ****ty products then you need to rectify it immediately and let them know of thier mistake. Its the same if you bought a lemon from a car dealer, or got ****ty merchandise from wal-mart. Please don't just be a tool and allow them to take advantage of you.