Hi Happyimmmigrant,
How long you were working with Company B and C after the rejection and what was the gap once you switched from Company B to C and then to Company A. If you were working with B & C after the denials then that might be unauthorized employment.
My understanding is you can work on the receipts and that's what the Law although you cannot work once you are denied. I have never worked on the receipts so i am not sure if my understanding is correct. Although i will recommend that you get all the receipts/rejections from Company B & C as it will help you in terms of providing explanations.
I am sure you will be speaking to a lawyer. Wish you all the best and let us know how it goes. Thanks