Honda — Major problem in bike

Dear Sir

I have purchased Honda Stunner CBF 125 (in gray colour) in September 2009, And in just 4 month it's creating problem, I can never go beyond 50 speed, it has pick up problem as well. Even i have taken it to Pragyan Honda Service Centre in Okhla New Delhi 4 times but still it's creating problem so i need to fix this problem as soon as possible so please take some action or else i have to go to the sr. manager of Honda, i am very-very upset with Honda and their services.

Regards
Ravi Kumar
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Email id : [protected]@yahoo.in