I wish I had perservered with my D35. I got rid of it for similar reasons. When a guitar makes you look a fool on an important occasion, and you've paid a lot of money for the damn thing, it really is bloody heartbreaking -brings out the Basil Fawlty in you - you want to hit it, and get your own back.

In retrospect, what I should have done is look hard and long for someone who really knew about guitar construction and Martins in particular - an be prepared to spend another couple of hundred quid. People like that don't grow on trees, and theres a lot of cowboys out there.

In a way Martin should be ashamed of themselves - doing this to their customers. When it stayed in tune though, it was the best guitar I ever had. But if you're hoping to make a regular income out of playing - just off the shop wall, they're a bit of a joke.
Get a Yamaha - one of the workshop ones for about two thirds the price of your Martin - may not sound as good, but it has more chance of staying in tune.

Where are you. I know a luthier in Nottingham I would trust to sort out a Martin as best it can be sorted.