Magellan GPS review: restocking fee of 15%

I've never been so disatisfied in being treated as a customer before from any merchant. I bought a magellan roadmate 1220 gps system from Sears store #1430 on11/27/09 sales check #[protected]. I brought the unit back after realizing that my son had purchased a different unit for me at christmas. I unfortunately opened the box to read the operators manual and I placedthe unit and operators manual back int the original box, unused and containing all original product packaging and accessories. When I tried to return the product, I was told there was a 15%restocking fee. I'd like to know how I could tell if I wanted the unit without opening thebox to seethe manual. The manager was of no help. Sears will not listen to my complaint. I would like to return the gps system with no restocking charge. I will wait for a reply in returning the unit since i can't get any help in resolving this issue.