New handset not working

I bought Motorola handset L6i on 20th of May 2007. From the very first week I started having problems with the handset. The keys stopped functioning. When I see an incoming call and hit Answer, nothing happens. Same with other keys.  The local dealer recommended to remove the SIM card and put it back in a few minutes. I tried that. It does fix the problem for an hour or so, after that the keys are not responsive again. I was not expecting such poor quality from Motorola.