Can someone tell me what the correct name for this is and where I can get a replacement?
After buying new hid bulbs, I found out this is the problem through checking it on both sides.

 

Looks like an aftermarket HID ballast made by Virtual Daylight.Looks to be a canbus type as well

 

Think theyre on ebay but do a search, To be honest .as long as you look for same wattage for bulbs ie 35w or 50w or even 75w , any make will work being aftermarket. All info should be on the ballast

 

No info on ballast but new bulbs I bought were 55w and they work in the other ballast. Think iv found them on eBay however one seller has them at £30 each and the other 2 for £11 which is making me think they differ somehow

 

And does anyone know what Canbus means?

 

i believe canbus is an operating system on the electrical side that indicates a fault with a bulb due to a change in voltage. i think lol. Not sure about the price difference. Cos its ebay its prob just to do with make and maybe quality

 

CANBUS: http://en.wikipedia.org/wiki/CAN_bus
A bit more than kevo says, but essentially right. Almost everything on the car "talks" to the ecu, which monitors it all for faults, and can usually store the fault and tell someone what is wrong.

HID ballasts are basically a large transformer with capacitive storage, and as such, you get what you pay for.

I'm unsure about higher wattage HID bulbs as yet, not seen any that are genuinely brighter, but, since fitting my projectors in the Scoob, have stopped reading up on them.

Try www.theretrofitsource.com for advice and parts.
although based in the USA, they are VERY good and will take time to help, plus stuff ordered is here in under a week.