I had a problem with my 2610 as well. All the keys on the left side had no feedback and the * (star) key was practically unusable.
So I steeled myself for a confrontation and went into the 7-11 where I bought it along with my box and 3 day old receipt.
By chance I got the manager. He took one look at the phone, played with the keypad then pulled a new one out off the shelf no questions asked. We switched the SIM card and checked the minutes right on the spot. Good to go.
It was a great experience. In fact I sent the 7-11 HQ a little note to tell them so.
Note: I think someone had messed with my original cell. I notice that I had more themes, ring tones and wallpapers on the new one. It also had all the protective screen covers still in place. I would suggest that new buyers just have a quick look at their phone before they walk out of the store – no big deal.