NCD and insurance premium refund

AK36

Hello, I am new here and this is my first post, just looking for some advice.
I had a car accident 2 years ago that was not my fault. My insurance company passed the case onto an accident management company as I only had third party fire and theft cover. This was to recover the costs of my vehicle as it was written off and undrivable after the accident.
The case ended up in court two years later and the third party driver was found 100% at fault. All my costs were recovered from his insurer.

I was told by my previous insurer (at the time of accident) that my NCB would be reinstated when the case was settled in my favour, my problem is my current insurer are making it difficult for me to do this. I have been insured with them for almost two years so I am asking them to reimburse the difference in premiums, as I paid £800 last year and £500 this year (both times the company said they had to put the accident down as an at fault accident until the case is settled).

They have agreed to refund the difference for this year's premium but are not agreeing to refund last year's premium. They also have not yet reinstated my no claims, they have just updated the status of my accident to not at fault. I am confused as to why this Is, as the accident was not my fault, but I paid a very high premium on the basis that they could only assume I was at fault until proven otherwise. I have proved it was not my fault, so surely they should refund the difference for last year's premium also? Or is this joy how it works?

Sorry if I've rambled on a bit just wondering if anyone else has been in a similar situation or knows the rules on these things. I have called my insurer and I am awaiting response to an email I sent over a week ago 😒