Just an idea… but if the sire/dam are known, give their akc numbers and we can probably find if they really didn't mean it or are repeat breeders giving same sad song.
PLEASE get your pup tested for Fanconi and PLEASE strip test and read up on basenji health issues.
I agree with Pat, but let me add one thing. When a pup is super mouthy, often the best you can do it let them bite in play but stop if too hard. Cara is a year old and the mouthiest creature I have ever owned. She bites her own foot and thigh, the bed, everything, when she is excited or frustrated. But although her mouth is on me constantly, she rarely applies enough pressure to hurt, much less leave a mark.
Think of toddlers putting things in their mouth, and you have a 9 wk old pup. It is normal behavior that you have to take time to change.
All that said, seriously cute adorable puppy. Congrats and welcome to the board.