how can i stop them from biting?

well as you know i have a female crested called daphni who is 16 months old now. my OH got a male and he is no 8 months old. they get along fine, follow each other when they are together, sleep together and share toys etc.

my problem is when they start playing with each other, mutley will hang off daphni's fur near her ears and neck, even if she is running, and now her hair has started to break and its now shorter on one side and its really noticable. obviously she isnt going to do too well in the show ring with one side really short hair, how can i stop him from hanging off her?

i tried to make a loud noise which worked for a while, no he just ignores it. and most of the time, its hard to notice because you have to be looking at them because hes normally sneaky and does it really quiet.

any help would be greatly appreciated.