OPT STEM RFE

[guy123fg]

I applied for STEM OPT for extension. I recieved my RFE asking me to provide documents regarding my employement history stating that if I work for end client, document must be signed by end client. I was employed by employer a from jan 12th to july 30th and employer B from August 10th to current. Employer a was fulltime but a consulting company . I worked at their office. Employer B is a contracting company and I am working in location C. I have my contract paperwork ,my all paystubs from both companies. But company B is unwilling to provide me classified information regarding their contract. I admit,they will not. So I asked them to get a template signed between them and my manager stating that I was employed with them and woking on position C. What other document do I need to provide?Is my offer letter from A, pay stubs from A, offer letter from B ,paystubs from B and contract sign doc will be enough?
My opt was to prove that I was not unemployed for more than 90 days but they requested doc to be signed by end client.My employer A and B aare not willing to give out classified company info about end client .Am I in trouble?should I ask them to submit those docs to me?And I am in NSC