Vauxhall Astra often gets stuck in gear,

My car has been getting stuck in reverse, first and second gear(the car will constantly move in gear with the clutch fully pressed down) and only comes out of gear when you turn the car off, depress the clutch and then start the car again. Recently had an MOT and full service and no faults or low fluid levels seen etc. Is this a clutch or a linkage issue? Just looking for some info before i take it to the garage and get done for a new clutch/gearbox