The first seller probably sent you a fat bike kit by mistake. Rim would be 2-3/4 inch wide, which fits your description, and motor would be over 5 inches wide at the axles.
Amazon will back you with third party if the guy did something like the above, sent the wrong goods, or sent damaged goods. Otherwise, he shouldn't have to take it back if you changed your mind or ordered the wrong thing,
If you buy it, don't put the electronics in the bag they give you. It will just cook the controller in summertime and kill it. Mount it on the frame somewhere so it runs cool. Cover the connectors so they don't get wet