SAGA do a reasonable offer of 3yrs fixed price premiums, as long as no claims are made.
I was with Direct Line for almost 20yrs and each year the renewal letter arrived with an increased premium and I would challenge it, they would drop it down to within £5-10 of the existing premium. Two years ago the letter arrived with an almost 40% increase! I challenged it but they refused to entertain any reduction, so I moved, to SAGA paying slightly less than the existing DL premium.