Greek GDP was grossly overinflated in 2008 by overspending in the public sector. Compared to 1990, Greece still grew 80% points more than e.g. France until 2014, so they really don’t have much to complain about.
Really? I'd complain quite a bit about a 25% GDP drop, regardless of whether it was "overinflated" to start with.
If that is the case, we can simply inflate it up and problem solved.