Sincere thanks to all for the expert advice and encouragement.
It is clear from all the input, and on further reflection, that I should have done a G/A. Wrongly, my mindset was "Get this bird down'' not "It's not looking good - time for a G/A". Things happened very quickly though and I guess after that first bounce I did not have the presence of mind to think G/A.
This was my fault as my instructor did remind me before stepping out of the plane of the go-around option. I certainly will be talking to him further about G/As and pilot induced oscilation. It seems that particularly in the 172, where the bounce/baloon can so quickly get out of control, that you should be ahead of the game and thinking about a G/A.
SAS: Airfield was not Parafield. but Aldinga, south of Adelaide. No problems with obstacles but because of the close proximity of the Willunga Hill wind and thermals can be tricky, as they were on day in question. Instruction there has been excellent.
Tomorrow I intend to talk further with my instructor about what happened and how I should have reacted. And I hope to be practising G/As.