Car accident 2006

My wife suffered a no fault accident in April 2006, when a parked car was hit by a articulated lorry travelling in the opposite direction. This caused a drivers side impact, totalling writing the vehicle off. My wife was thrown from 1 side of the car to the other and was lucky to survive.
Luckily the vehicle was insured with Norwich Union and there solicitors began proceeding against the lorry driver on her behalf.
We moved to spain as a family with 2 young children in July 2006.
Although my wife has returned to the uk on 2 occasions to see an independant Medical proffession who told her she would be fine after a period of 9 to 24 months.
This has not been the case and the solicitors suggested we take private treatment in spain.
My wife has undergone Xrays on her lower back and right shoulder. The findings being 2 collapsed discs in the back causing a hernia and tendonitus in the shoulder. They recommend keyhole surgery in both cases to relieve the pain.
Please bear in mind this is now 2 years after the accident.
She recently visited the UK again and was seen by a specialist at BUPA who said there could'nt be anything wrong and was against any operations as this was degenerative although he was unable to read the scans properly as he needed a radiologist.

My wife and i are now not knowing what to do next as the other party solicitors have given us an interim payment of £1500 when the scans were done.
But they are now refusing any further payments for any operations unless we can prove that these problems were caused by the accident 2 years ago.
They have all my wifes medical history which does not show any problems with the back or shoulder prior to the accident.

A little advice at this stage would be most appreciated.
Thankyou for the forum

Mr S