A burning smell and a failure for engine revs to translate into forward motion are symptoms of a failed clutch. It may have been caused by driving style but it is not correct to suggest that a new car could suffer from a faulty clutch, however if that was the case it should have been apparent from when the vehicle is new. An independent report should be just that - carried out by an independent party, however it may be that the dealer is suggesting they would not accept the opinion of a report if it did not come from a SEAT dealer. An independent report may only reveal that the clutch is heavily worn resulting in the failure, and may not uncover a manufacturing fault. You may wish to consider the cost of an independent report against the cost of replacing the clutch. Although your driving style may not have changed, different vehicles may have different clutch biting points, and even the slightest pressure on the clutch pedal while driving may cause a degree of engagement which could cause it to wear prematurely.