Settled a similar claim to this last year, in the accident that I dealt with lady parked and was exiting her vehicle and 3rd party was going past in slow moving traffic. Lady maintained that 3rd party was to blame - a motor assessor sorted it all out - 3rd party wasn't to blame, parked vehicle was to blame as she didn't exercise due care when exiting. Have you informed your own insurance company - they should be able to fight your corner for you.
Assuming that the events panned out in the manner that you described, the other persons insurance should settle for your damage, depreciation, car-hire for down-time, inconvenience etc. I'd give them another bell, could just be Easter back-log. Insist on an assessor for your vehicle and give them a strict time limit to get things moving - (stating that you have taken legal advice chivvies them along too!)