What can i do? the police arent doing anything!?

ok so i was out on my sled due to the snow in the uk which is awesome :). but then 6 or 7 chavs came up to me and my two Friends and 2 of the chavs where like 17 or 18 and the younger ones who where like 13 or 14(my age) said give me that sled now and stuff and kept threatening me and i refused to give it to them as my dad had spent along time making it. then they got angry and 3 of them jumped me(as me and my Friends aren't really " 'ard" as they would probably say) they punched me repeatedly in the face and took the sleigh, when i got home i told my mum and dad and they rang the police but they didn't do anything about it! what can i do?and why aren't they doing anything!