Sometimes an insurance company if it doesnt really want you to renew for whatever reason, say lots of claims in the area where you live, you live near to an area liable to flood, you have a car thats become expensive to fix, they are easily stolen etc, it cant really refuse to quote you cover, but it will quote you a high amount in the hope you will go elsewhere, I used to work in that industry and we did just that, get rid of all the undesirables and high risk to other insurers.
So if your quote has gone up threefold this year that could be the very reason, youve suddenly become undesirable, and not necessarily through your own fault.

I had a Volvo S60R that was costing me £400 with More Than. When I got the FL2 they wanted to hike that to £750! No claims in like forever, and stacks of NCB (I'm 45).

Went to Hastings, and got better insurance (no excesses for starters) for £400 with the missus added too.

I'm currently with Hastings, last year fully comp was 270 quid. Got the renewal letter yesterday and they want 355!! that's with 9yr NCB. Ive been looking online tonight and Hastings are still the cheapest but at 300 quid. I will be phoning them to see if they can match the online price unless I can find anywhere else cheaper. Black MY2013 SD4 GS Auto, Wood Company Armrest, Freel2 sticker.
Gone MY2010 Freelander 2 Manual TD4.e S, Alaska White.

With M&S insurance - last year I paid £202 and today the renewal came in at £253 a 25% hike. Just off the phone and they have reduced it to £230 for exactly the same cover. Comp cover with spouse on the ticket and £250 excess. Judging by some of the responses to this thread I seem to have a good deal  MY 09 GS manual in Lago Grey, Wood Co arm rest and side bumper strips - now sold.

MY 15 SD4 SE Auto Orkney Grey with colour coded Bumper Door Mouldings