So what can be done? Perhaps not much.
However, that being said, these are my meager suggestions:
1. Write into the shtar borerin a clause that this Din Torah is subject to review by Beis Din X or Rabbi Y.
2. Network names of unscrupulous borerim. If you find out that the other tzad has chosen one, you might be able to then compel him to appear in front of a local Beis Din.
3. Not easy, but if you can, when you take a job or enter a contract, specify that all disputes will be adjudicated by Beis Din Z.
Any other ideas?