2005 plate 2.5 6v with LPG conversion - got air intake probs - is worth fixing it?

Hi
Not had Freelander long but got this problem almost straightaway.
Took it to local garage who always saw to our other cars so we trust them to do a good job but they don't want to do anything with car coz they aren't used to them.
Just want how much it is likely to cost if we take it to a Landrover dealer?
Any help will be a big help.
Cheers
Mic

The cost at the stealer depends on what the dealer does or you ask them to do? If you need to ask for help? It's polite to introduce yourself the tell us exactly what you need help with??