I assume the second service is being referred to the one done at 17,000km's. That is a LOT of km's for one oil fill to endure. Although i do not know what exactly has gone wrong with the turbo, but a 17,000km run oil would have done the turbo no good either. The fluid bearing, by its very design, swims and spins in a bath of oil. And if the oil isn't upto the mark in terms of strength and lubricity, the turbo can suffer. FIAT has already prescribe a severe interval of 15,000km's, which i wholeheartedly disagree with and pressing the oil more is not advised at all. I personally believe in 7500km oil changes. Hope your Punto is back to full glory soon.