Do the courses, work the two years. That's 2 years more experience WITH the qualifications behind you, get a better paying job else where in two years time.
Or just point out there may be some other mech's that hadn't had the opportunity to get the training and perhaps it would be in both of their best interests to send them on a course instead of your good self.
As with all jobs there is always a degree of politics you need to be able to deal with, this sounds like a good opportunity for you to learn some new bollotics skills, maybe they could send you on a course?