you can get all the kit to fix it and a crystal too for less than the cost of a repair. For example:

http://www.ebay.co.uk/itm/Brass-Alum...item4d21aa38be

measure the crystal carefully and then use someone like Cousins - if it's not a standard fitting they usually do something,

https://www.cousinsuk.com/

I know it says trade only, but they are very helpful and don't ask.