Please help! Is it really "normal" for an Opel Corsa 1.4 to get its 3rd engine at 60 000km's???

My Opel Corsa was bought in January 2008, in October 2009, at just under 30 000km's the engine
failed and a new one was put in as it was still under warrentee. Now, in 2013 the engine started to
cut out again. The car was sent for a service, which after they gave 2 quotes for either a new engine
(R47000) or a reconditioned one (R59000).  After many calls I found out that the car never received a
brand new engine, but a "rebuilt"one as there was no new stock at that stage.  General Motors that
this is common practice and that it is not impossible for an engine to fail at 30 000, and also not
impossible to get a 3rd engine at 60 000kms.  I have another car which I have had for 12 years and it
has never given any engine problems.  Can somebody please help me.  Is it legal to not put a new
engine in, as it makes it then impossible to trace if there was a problem with the engine as it is not
new.  General Motors is now saying that we must take the Corsa in so that the engine can be
stripped to find the fault, but this will be at our own cost.  Please, if anybody can give me advice I will
appreciate it!  It feels like they are trying to hustle money from a woman who doesn't have it or the
knowledge of cars.