First time poster guys hopefully someone can assist. I have a 2009 corsa d with hydraulic clutch. For last month I have been having issues with my clutch after having it replaced. Car drives fine for a week and I can get gears but after a while I can't select any gears. It's usually followed by oil leak in engine bay. Only get gears when engine off. However after pumping the clutch I can select gears when car idling. Have replaced master cylinder twice and slave cylinder twice. Bled system thoroughly to ensure there is no air in system. Like I said after pumping clutch I can select gears but there is always a leak in engine bay. Pedal is ok and returns. Break fluid reservoir stays full. Had car at 3 mechanics already. Same problem every time. Any assistance is welcome.