If you had been able to replace the bush on its own, there is a "how To" -
Link
I have done this twice.
Last year I also needed to change the whole arm after the MOT failure.
I had two problems:
Firstly, the tools and force required to crack the sub-frame bush taper was immense and necessarily violent, even with the weight of the car on it.
Secondly, as I purchased the bush & wishbone arm separately, it was such a tight fit that I needed to heat the bush in hot water and freeze the arm in the freezer in order to get the parts to go together even with washing up liquid to lubricate it.