I would check the price comparison websites.
I was with Direct Line - and had been for the past 6 years. This year i was expecting my premium to go down to around £300 as i am now over 25 (and this is what direct line told me). Instead it was increased to just shy of £600. I should stipulate that 3 years of my no claims was as a named driver - so i was not able to carry these over to another company - i could only carry over those years i was the policy holder. Yet i managed to find several quotes at what i was expecting to pay with direct line AND as an added bonus, they actually had a lower excess and better coverage!
Direct Line refused to discount my policy even though we have 5 cars insured with them. It has taught us a valuable lesson and when we receive renewal notices through, we will be checking to see who offers the best deal and not just assuming like we had previously.
Direct Line's defence was that all insurers had increased their prices by 20%. I pointed out that it was closer to 70% raise and if you counted the price i had been told i would pay (being over 25), it was actually a 200% raise. How they can justify this i dont know.
Remember, Direct Line advertise you wont find them on any price comparison websites................no flipping wonder! They'd never get any customers.