radio antenna

The diversity unit in my boot well has died due to the common water in the boot problem because of a dodgy air vent. Hopefully (fingers crossed), the leak is now sorted but the radio reception is completely knackered. Have tried another A2's diversity unit in it but reception is only mildy...

I was driving my 1.4TDi SE a while back, whilst it still belonged to my mum, when all of a sudden the radio reception disppeared. Having read some of the other threads on here, the radio aerial appears to be in the back windscreen. This hasn't been damamged, and seeing as it was working one...