I got a new Fiat Punto a few months ago and the suspension has been squeaking on it. It's hard 2 describe but it sounds like a kind of bubbling (like boiling water)/squeaking. What is this problem and is it serious? Secondly, can I just ring Fiat up and tell them I'm dropping it in (what paperwork will I need considering the plate clearly shows its under warranty?) and will they care that I have put my own head unit amp and sub in?