Are you able to just change the bulbs? If so then change them all for LED.
Be careful, not all LED bulbs are dimmable.
Good morning Diane, my name is James.
There is a EU directive to phase out halogen bulbs, hence there is a push to sell LED's. You can still purchase halogen bulbs on ebay and amazon for a fraction of the price such as here.
However LED's are cheaper to run and last far longer, should you wish to use LED's, you can mix and match, but as Andrew suggested earlier you need to make sure the ones you buy are dimmable such as the ones here.
Please let me know if you need any further assistance.