Were you talking about this a few weeks ago?
To me, it sounds like a faulty ballast or something...
In that case you have 3 options.
1. Replace like for like - not sure of the price, but looking at mucho dollar i'd think.
2. Turn your lights into regular halogen lights, bypassing the HID kit. This will cost you about a fiver plus bulbs, and a few hours DIY work. Can talk you through this if you want to go down this route - just PM me...
3. Buy an aftermarket HID kit, and replace your stock HID kit with it. These kits start at about £40 on eBay, but im not vouching for their quality...naturally i'd assume that the more expensive kits would last longer. This last option is probably what i'd go for though.
Either way, this is all easy enough to do yourself - i wouldnt take it to a garage for this.
Hope this helps...