That quote really is worth sending to the company concerned. A figure that far out just has to be an error. Maybe an extra 0 and it's meant to be 1700 quid?
I got quotes on Escort Cosworths when I was bored one night for less than that - and I was 17/18 at the time. Was pretty surprised as I didn't think you could drive one of those at 18
I don't think it is an error to be fair. But if it is I know of at least 3 or 4 people getting these silly quotes from companies. Including myself, a years car insurance for £12000something?!