Let me tell you a story - we bought a 2001 multipla with very few miles on it. Loved it at first, then it rained and the problems started - the sunroofs leak like a sieve, the dealerships know all about it as it's a very common problem (and not just on Multiplas). The design of the sunroof action is such that it tends to damage the seal as it closes, and there's no reasonably priced seal available to replace - when we first contacted a dealership, we were quoted over £1000 to replace the entire sunroof! I contacted the Fiat Customer Helpline (0800-717000 or 0800-3899119) to see if they would do the decent thing and replace it FOC, as I felt we were suffering because of their incompetence (a good vehicle manufacturer would have identified these problems during testing & development, and put them right - I believe what Fiat do is termed 'customer validation'). After many phonecalls to the dealership and the helpline, the best they could do was to offer to sell me the part for just under £300, and pay a bit of the labour. So then, £300 to fix a leaky seal, which ought to cost about a tenner if they had done their job right in the first place. And it stained the rooflining and damaged the electrical switches mounted in it - I should point out that the sunroof switches fizzle and spark when they get full of water from the leaks, and it's a definite fire-hazard!
If you're suffering the same fate, can I suggest that you also contact the Fiat helpline and let them know what you think of their sunroof durability, and the unreasonable cost of putting it right, perhaps they might be shamed into some sort of action.
I reckon you can a judge a company not on how many mistakes they make, but how they deal with them afterwards, and Fiat haven't impressed me much. Needless to say, I shan't be buying any Fiat product again.
Thanks Fiat, you're all heart.