Concearned about acting

I talked to Emma yesterday after we'd given up on filming for the day. She was very concearned by the quality of our actor for 'Gary'. We'd only attempted one shot, and i think we'd done over a dozen takes. He's not a trained actor and although he was happy to act for us, which im sure we're all grateful for, he's lacking in a lot of confidence needed for our script, he may not have seemed so bad if he'd got other actors to bounce off of but really we need to find someone else.. Im quite worried that we're really running out of time for casting, we've only got 10 days to go before our presentations