Gear trouble help appreciated

Was driving my octavia estate yesterday, went to change gear and clutch pedal wouldn't come back up and couldn't select any gears so ended up stranded, AA guy seemed to think it was hydraulics but got it to a local garage and mechanic seems to think this isn't the problem and said he may need to take out the gearbox as when he pushes the clutch pedal in it comes back out on its own now.

Getting a bit panicky now cos its starting to sound like a big job and if it is thinking of using the sale of goods act as the cars only been out of warranty for 6 months.

Anybody had a similar problem? any help, advice or potential solutions would be very much appreciated.

Thanks in advance