Cognizant Technology Solutions — Bgv negative

I got Offer letter from cognizant. I served my notice period. Right now I am jobless. My first company didn't have PF while I started my career. Later on 3 months before I left they have started to deduct PF which is discrepancy for bgv. They have asked me to share the mail chain where offer letter is shared. Thing is I have received it manually. So to assist them I have shared my bank statements during that tenure. They are saying if I couldn't share the mail chain where I received offer letter, my bgv will be negative.