I would try a local tech rather than trying to do it yourself. I find it rather odd that the so called tech at that particular store wouldn't do it. Then again it really depends on if they are an actual tech. Don't get me started.
As stated originally, I would try a local tech. It would be wiser than trying to do so yourself and if by some odd chance they do any damage in the process they are responsible for fixing said damage (on them) where as you would be stuck spending more to repair anything you may damage during the work. Also, the tech should give you a warranty. It may not be for long, but it is better to have one.