Munich to Mayrhofen

I'm taking a trip to Mayrhofen on Jan 3rd and am finding trying to organise
transfers between Munich and Mayrhofen a nightmare. Does anyone have any
tips on what to do for tranfers? I was looking at taking the train but I've
been told it's an arse to do as you have to take 2 trains to get there. I
was also looking at possibly hiring a car but they're asking £300 for 2
weeks!

Thanks in advance.

MM.