I797 A orginal document is retained by current employer

Hi, I have recently transfered my h1b from company A to company B. I am having the orignal I797 B document form employer A.

But my current employer has given me only the first page zerox copy of I797A form. And now if i transfer my h1b to company C . will it be be any issue for me to apply for GC or stamping in absence of orginal petition from employer B.

Kindly reply and please suggest how can i get back my orginal I797 A documents from employer B.