They are just killing time for the inevitable: a debt relief.
That is a foregone conclusion. In the end, at least some of the debt has to be written off. Without that, how do you expect the Greeks to pay back this huge amount? Their total population is just 11 million (and rapidly declining). The troika is only damaging its own chances of getting the money back, by saying that it will not allow any change in the clauses.
If Greece has a small budget surplus (as one of the conditions was), they can chip away at the principal.
But the government doesn't even want to agree to this.