Okay. As others have already pointed out, your age, combined with a larger vehicle is not a good combination for a cheaper insurance quote.
First of all, go onto a comparison site, such as Confused.com or Go Compare. Never accept your current insurers renewal price.
Try increasing your voluntary excess if you can, as this may help to bring your premium down.
Direct Line also do black box insurance, so it might be worth giving their Telematics department a call to see what they can offer.
My DD had a new 1.0l car when she was 17, and with me and my DH as named drivers on the policy, the most she has paid is £1400 (and that is fully comp, with Direct Line on a telematics policy.
Also, if you able to protect your no claims discount, this is worth doing for the extra few pounds.
Look on the bright side - when you are an old codger like me it will only be a couple of hundred quid to insure your car!
Best of luck - I hope you can find a better quote soon.