2013 Ford Focus Trend transmission failure

My brother and sister and I purchased a new 2013 Ford Focus Trend for our 65-year-old mother. The car was 18 months old when it encountered its first auto breakdown. At first they told her it was the way she was driving the car and made her look stupid. All up it has had four separate repairs including full transmission replacements, and after every time we were promised “the problem is definitely fixed this time”. It was in the workshop for weeks. The last and final straw for us was on Nov 11th 2017 when I got a phone call from my mother in tears, stuck in the middle of an intersection in Geelong with no gears. Long story short, the car is now at the dealership we bought it from (and who has done all the repairs). They have “repaired” the car for the fourth time and has been ready for pick up for two weeks but my mum, who is now 68-years-old, cannot and will not get back into that car! She is physically scared of the vehicle and gets visibly upset at the thought of it. The dealer has hand-balled it to Ford Australia and they have come back with an offer of an $8850 changeover cost to us to put her into a new car. Part of this equation was a trade-in valuation of a mere $5000 for her car, a Trend with 93,000 km and in great condition, apart from the obvious. I feel we are being kicked in the guts and aside from taking legal action we feel helpless with our options. We don't want this to drag out as mum’s state of health is a great concern. Do you have any advice on our next course of action?