2005 Ford Mondeo rear subframe bushes

hi guys still having trouble with my mondeo i got two new tyres fitted on front and it was pulling badly to the left so got it tracked but did not solve the problem so i got it tracked agin elsewhere and had put the original steel wheels back on and it still is the same but now it seems like the back has play in it aswell.i was told it could be the rear subframe bushes that might need to be replaced and was wondering if it is a big job i just thinking of the labour costs that might be involved.