As already stated a quick check with the KC re: the litter registration will allay your initial fears that they
have been registered. I hope that all is then well with your peace of mind.
Then it is purely down to the breeder for some reason not getting their finger out.
Unless there are complications I've never understood the pure laziness of some breeders, not having the KC papers ready on collection with the pups, to me it is unnaceptable they take a few days to be delivered once registered. The KC transfer papers and pedigrees in many cases show the puppy owner that all is well and that they have their
pedigree pup within the rules of the KC which is why the breeder is sought out by the puppies owner in the first place, why some are then denied the proof of this and made to wait I just don't understand, of course it is important that the new owner has the transfer details, the free insurance and the pedigree on collection, that's why they went to the breeder in the first place.
I feel very sorry for you that you are left waiting and wondering - totally unacceptable IMO.
If the litter has not been registered and you are being bluffed, then trading standards and the KC need to be told immediately - hope this is not the case.