Mouthing everything - suggestions for deterring?

[Crayola kiddies]

Perhaps your not saying it with a stern enough face and voice... Every time he puts something near his mouth say "NO NOT IN YOUR MOUTH" loud enough to startle him...also speak to the parent again and say "I need you to stop him from putting things in his mouth at home .... Anything and everything ... Toys books fingers everything but food .... This is not teething this is a habit and a bad one .... He is now biting other children and it needs to stop .... Other parents are not happy their child is being bit and rightly so....I need to see some improvement within two weeks and if we are both stressing it all day I'm sure that will be no problem...." And if she is not willing to work with you then hand them their walking papers because you have an obligation to keep the other children safe and they are not safe if they are being bitten ..... You run the risk of losing your other families if you don't put a stop to this kid