it's entirely legal to bring in a product you aren't satisfied with within a the first week or so in exchange for store credit or in some occasions cash, subject to the discretion of the store manager.
Being an honost guy has nothing to do with recognizing a piece of shit hardware you bought with your honost money and applying your custumer right to have it replaced with something that does work or is worth your money
more than a week passed. And also i don't really see why i should consider the router a piece of shit when it works flawlessly and wonderfully with all my 4 pc, notebooks both with windows and linux... It just and only the X360 not working, i can even keep all the pcs on at the same time with no problems. anyway i'll experiment with cable in and maybe i'll try to sell the router to some friends afterwards.
I had problems with Belkin routers in the past, but I think most of them a shit these days. I use a Linksys, but I don't know if I can recommend the newer ones. The antenae are internal and they seem to drop every now and again and need to be rebooted.