Insurance advice - Honda 125

My eldest is due to get his insurance renewal in the next couple of weeks - his bike's a Honda CBR125.

He's had 2 own fault accidents in the last year including a total loss on his last bike - another CBR125. No injuries or 3rd party claims.

So far the cheapest quote I've managed to get is £1700 fully comp - but one bunch quoted £5700!!

I've tried the comparison sites and a couple of independants but the £1700 figure is the best yet - bike's worth around £2500 replacement value.

He's due to take his parts 1 and 2 in the next couple of weeks but at this rate he won't be able to afford to keep the bike on the road.

Any suggestions or ideas would be welcome.

Cheers

G