gearbox/trans issue

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i have recently bought a 51 plate cooper, it only has 16k on the clock but the gearbox feels really notchy, when letting the clutch out i get to about 80% up an there's a small clunk from the trans somewhere also if i perform a steep hillstart or put heavy load on the clutch i get a strange whining noise from the front of the car, the garage is taking it back to look at and repair under warranty they have told me they think its the clutch release bearing? any other ideas ? i dont want to get the car back and a few weeks later out of warranty the gearbox fails, thx

[smc]

Perhaps u can insist a good rectification works and should there be the same problem arises after warranty, they should be responsible . Cheers