ghd's stopped working after crackling sound?

ive had my ghd's no longer than 4 months, and they've worked fine.
ive had no problems until the other day when i turned them on, and i heard a crackling sound coming from them. the plates didnt heat up and eventually they just stopped working and the light turned off.
i haven't mis-treated them and have always looked after them.
i have no idea how this could have happened, and don't now how to go about trying to fix them as i do not know what the problem is.
is there anyway you could give me a solution and mabye give me a price if you were able to solve this problem.
thanks