Renewing / Switching insurance with outstanding claim

just wondering if anyone can offer any advice / clear up my confusion. I had an accident back in July 2015, one week after switching to my current insurers. The accident damaged looked minor, other driver hit me, we decided to leave it and not bother. Got home, found damage was more severe, decided I needed to claim, made attempts to contact third party. Anyway, went through my insurers, showed dash cam footage, they decided it was 100% not my fault. Told me everything would be fine and not to worry. Then in september 2015, claim was passed to Harper MacLeod, a solicitors, to deal with the claim as other driver hadn't notified insurance. 

Claim is still outstanding now, nearly a year later. Harper are useless, they keep saying they will chase and never get back to me. My current insurers wont chase Harper on my behalf. It was hinted that I'd face higher premiums and temporarily lose my no claims discount until it is resolved. My Insurers wont tell me how it will affect my premiums and tell me to contact Harper. Harper tell me to contact my insurance to discuss... They also advised I dont chase them for an update and just forget about the claim and wait for a letter at some unknown time in the future telling me its resolved...

So My questions -

• I dont like my insurers, feel they are useless and haven't supported me in my claim. Can I leave them with an outstanding claim still open?
• If I leave them, how will this affect me getting insurance with other companies?
• Would it be cheaper just to renew with them, and less hassle? Will I lose my No Claims as a result?
• Why should I face higher premiums and lose my No Claims discount when they are all in agreement that I'm not at fault?

I'm a young person so insurance isn't cheap, but it's not expensive either. I'm currently paying £107 per month at the moment. When it's time to renew I was expecting to make use of my 2 years no claims discount and also expecting costs to drop to £60-70 per month. Now it's looking like it will go up to £150-160 per month.

I can't really afford a cost increase. I feel a bit stuck for how to handle things or what to do, I have an insurer who isn't interested in helping me and a solicitor working on their behalf who are telling me to no bother about the claim... Can I leave, do I have to stay with them, what can I do to get this claim sorted out. I don't have a clue and am quite frustrated.

My insurers are Churchill by the way