Thanks @Mapantz, I'll send them an email.
I have found a vue sensor suite from weather spares for £125, but it's out of stock, and the model numbers don't seem to match up, so think I have a different revision.
As you said, replacing the whole ISS is quite costly, cheapest I've found is over £200, which for that price I may as well sell the whole Vue as faulty and put the proceeds to a Pro2 or alternative brand. I'll see what ProData have to say though before I decide what the best route to take is, Thanks!