Complex sentence: Due to the driver not being found liable nobody was responsible for Sophie's extensive medical costs however the driver's compulsory third party insurance provider, NRMA, covered the costs ex-gratia.
Split into simpler sentences: Due to the driver not being found liable nobody was responsible for Sophie's extensive medical costs. However the driver's compulsory third party insurance provider, the National Roads and Motorists' Association (NRMA), covered the costs ex-gratia.