Plz help. Bajaj Pulsar 150 dts-i problem?

I own a Bajaj Pulsar 150 dts-i which i got in Mar 2011. It was working fine up untill now but since last week it's not running freely and smooth the way it used to be. When it speeds beyond 50-60 kmp/h, I feel some sort of vibrations and heat near footrest. I took it to the Service Center twice, first they told it's bcuz of the Extra Air in Tires. When I took it for the second time they said it's a Alignment problem. I did everything what they told me to do and spend bloody 400 bucks on it. But it doesn't fix the problem. Bike is still vibrating. Please guys give me some suggestions, what do i do to get it fix. Whosoever answers the best will a 10 points from me. . . .