Hi Phil...welcome to the club!
That's a real shame, nothing worse than having to shell out money within the first year especially as you have a warranty.
However, if the air con only stopped working over the weekend, that would suggest that the loss of gas is quite recent. Only thing you could try is to request they charge you for the the condenser and they make a claim for labour through the warranty company (suggesting that the condenser lost gas over time because it was porous, or some other reason). It's worth a try!
Let us know how you get on with it
Cheers Trevor - Admin