
Once the Kennel Club have received a letter to lift the endorsement they do so and confirm by letter ( and email if you email the signed letter/form).
The loss of confirmation letter will not make any difference and you should be able to register the litter if in fact the endorsement was lifted.
If the KC have confirmed they have the request to lift then they should be updating the record shortly, and you can then register your pups.
Have you actually had your registration application refused???
Did you ask the KC to upload the endirsement lifting details so you can register your pups. I would expect the person on the phone would have pushed it through, due to urgency.
I would ring again, or try to register once more.
It is taking 28 days+ for litters to be registered, and then longer to receive the paperwork.