By rejecting austerity and failing to implement reforms, you don't leave many choices
They didn't reject austerity, they had years of austerity which caused the economy to downwards spiral.
Austerity = taking money out of the economy - how can you expect the economy to do well and grow if you take money out of the system? Answer = you can't, you get what happened in Greece and the same has happened over and over again when the IMF has forced countries to wreck their economies just to pay back the debt.
IMF don't lend money out of the kindness of their hearts, IMF are heartless bastards who lend money to gain control of the country they are lending to, inevitably they want these countries to put their resources into the hands of conglomerates run by their mates. IMF don't give a flying fuck how many people starve because of their policies