I was in the same position as you recently but my accident was over three years ago, basiclly a lady crashed into me on a roundabout, it was a pretty bad accident and she was totally at fault. Like you I took BMWs advice and went with a claims management company who took over the running of my case.
I was delivered a brand new 325i E93 from Scotland as they didn't have one locally, at the the time I had a 330d. I had the car for 6 weeks and needless to say the rental costs were scary and TBH the only part of the claim that the thrid party objected to, long story short it went to court and the Judge basically said the claims company had done nothing wrong and to pay up, they appealled and again we went to court and again they were told to pay up which they did in the end.
As a guide the hire costs where probably about 2/3 of the value of my car before the accident.