Vauxhall Astra Club, Automatic, 56 plate - Failing gear box, old recall?? Coolant in gear box - kathym.uk

I bought the car 2nd hand in February 2011. In the last few months the car hesitates with increased revs on pulling off then suddenly lurches forward, hesitates reversing, doesn't switch well between reverse and drive, changes gear at high revs (60mph still in 3rd gear). Found out today (by chance) about the old recall regarding coolant getting in the gear box; a Vauxhall garage confirmed that my car went in for the recall work in 2009 but chap commented that they would not know exactly what work was done, ie was radiator changed etc. Is it possible that when the radiator seals were done in 2009, the damage was already done and water had already got into the gearbox? Is there anyway of proving this and getting anything from Vauxhall towards new gearbox that is now needed?

When last serviced the mechanic mentioned there was swarf in the fluid, which I have since been told could be a result of coolant boiling, condensing into waater and then rusting the gearbox - is this true/possible??

thanks for any help