I feel like making a complaint to the store, I nearly bought one of Pepper's siblings as well, its likely they're all pregnant and they all have the gene it's sad to think of a lethal pig in a home that isn't aware of them existing
Sadly not all that rare. I hope that @furryfriends (TEAS) can give you tips and you can find a dental savvy vet or one that is willing to learn to keep the baby alive and going.
If you drop something behind the baby's back or clap your hands and it doesn't react, then it is deaf.
I would certainly complain to the store, best in written form to the store manager.