No, they said that if you buy the phone from 3 you need to go to them for whatever problem!!
Is this true?
my problem is vibrator (apart form the battery which... lets say the update will "fix" as they did last year).
Your warranty is with Apple. If the phone has a genuine fault or defect they will replace it on the spot. You don't specify exactly what is wrong with the vibrate function. The chances are its something that Apple will replace the phone under warranty for.
I'm surprised Apple wouldn't help but technically the contract is with Three UK, so Apple could send the person back to the store.
I'd book another genius bar appointment and have another go.