I think my 3 week old ferrets have got fleas what can i use to treat them?

they have got little dark brown /black bugs on them. i have treated my other ferrets for fleas but the shampoo ive got says that the ferrets have to be 12 weeks or over. i dont want the baby ferrets to die off these bugs so can some one help me and tell me wot i can use on them. at the minute we just keep changing the bedding and using a bit of sticky tape to get them off the bvabies wen we see them as there has only been a couple and its to hard to get a hold of them to pull them off. please help.