The dealer tightened the bolts on the bar receivers too tight for you. Do you have some wrenches with you? If not can you borrow some or get someone to loosen them for you? Look in the manual for the recommended torque range for those bolts and set it to the lower end. You aren't doing anything wrong, just looking in the wrong place for the problem.
Loosening the bolts at the bar receiver will not affect the sway damping ability of the hitch. Equal i zer is a great hitch so don't give up on it, just get it adjusted correctly.