Try Aplan, they're pretty good, had recent dealings with them, they beat my original renewal by £30 and with lots of extras, but I had to haggle!
Not sure why you're getting quoted £3000 though, that's crazy. Have you literally only been driving for 18 months? I know the prices have shot up for new drivers in the past few years, but it shouldn't be that much for a van surely. Might be wrong though.