Wrong Diagnosis resulting to engine seized

On the 4th of February 2016, I took my vehicle for repairs and service subsequent to problems experienced with steaming window screen. The diagnosis was a leaking coolant. 3 days later the repairs were completed and payment of R 4,400 was made, I collected the vehicle. Same day on my way home the vehicle got stuck and tow truck was sent to collect the vehicle. This time the diagnosis was a faulty fan as the fan switch had to be replaced. The warranty paid for repairs and I collected the vehicle. Again the same day I stuck few meters from the garage. When I went to fetch it o got home and notice the coolant was finished. I was ask to bring it back and work had to be done on the engine. On the 14th March 2016 when I went to check the progress of the vehicle I was told that my engine had seized and cost to repair it is R 50,653.89 (exclusive) and service manager was fired therefore I need to deal with other service manager. If I think about this whole ordeal I suspect negligence and I can't be liable for engine seizing while my vehicle was taken for a simple thing. <br> The service garage I receive bad service from is Ford Fury Woodmead, Johannesburg.