yes... and the way out ...
You will have to provide the prior employment letters detailing the experience in line with what is mentione din the LC. IN case u are unable to get the employment letters from your prior employers, you may aquire the similar letter from your co-workers in those employments on the employer's letterhead.'
In case you cannot get it from the coworkers still with that employer, you may get the similar letter from co workers on the letter head of the company they are currently working in.
Preferably get all the employment letters notorized. I read somewhere someone got a RFE on a letter and after submitting the notorized employment letter he got approved.
Hope this helps
will_get_there