Thanks for all the feedback, the one i have currently is called 'Type VR' , i can get my radio to work if i stand outside and hold it down (not ideal when driving), but i think the rock hard suspension might have something to do with it as it knocks it about a bit.
Type Vr will be a rubbish aftermarket one. As others have said, you can't really beat a standard aerial for reception.
If you go on eBay and type in "punto mk2 aerial" you will see loads of new standard ones. You may just need the aerial part, or you may need a new base too.
It's very easy to fit shod you need to replace the whole unit!