Any gear from 4th upwards at 2,000rpm should do the same. 4th is generally better as you're doing a manageable speed (40mph?) and accelerating up to 60 or 70 is not usually a
problem. 5th and 6th might mean you reach higher speeds, and also 4th tends to have more guts so will
help make any clutch slip more apparent. Clutch slip has no relevance to ESP. That's simply you losing grip on the road. You should only do it where safe/dry and in a straight line. ESP shouldn't factor when a clutch slips. 2000rpm - floor it - revs rise, no or very little acceleration to match it - That is all. Should be no fluctuating off throttle - clutch slip only happens when on power, full power basically.
Clutch is almost certainly a consumable, but a pretty new one on a stock pd170 should not be slipping and I would be moaning to Seat if it was so early on in life.