you say he cut the end off,

cant you get a new end for it and reattach the wires?
even saying that, i cant imagine it to be too hard to get a cable from behind the stereo to the arial

 

i did try that, but unfortunatley he cut it so dam short it was a right pig to get my soldering iron in the dash to put a new end on, i did manae it but only after burning myself a few times i have got a little extender on the end but it still doesnt work.

the only problems i can see is getting the headlining to go back up without looking naff

 

headlining shouldnt be to bad if you do it right.
if you take out the glove box you can probably get to the cables a little easier. instead of doing it where the stereo is meant to be