90 days is the period of time in which the insurers have to make their investigations without the threat of early litigation (Woolf reforms) After the 90 days are up, your insurers (or indeed your uninsured loss recovery company) can issue proceedings against the lady who caused the accident. These cases rarely actually get to court, as it makes economic sense for the insurers to settle beforehand, but do make sure that any of your out of pocket expenses are included - this would include your excess, loss of use of your own car/cost of hiring a car whilst yours was off the road, loss of earnings, injuries etc.