2003 Mini S - Air Conditioner Line Change

[KCNissan]

I have a 2003 Cooper S which the AC is no longer cold. I took it to the dealer, & they charged the system with dye & said that the AC line under the dash has a pin hole size leak. They said they have to remove the dash to get to it & it's a 8 hour job & wants line $2000 to do it.

Has anyone had the this problem? Or know any tricks to replace the line under the dash? Or tricks to remove the dash?

Do those AC Charging fix-a-leak servicing cans really work? The AC did stayed cold for like 3 months after they charged it last.