When you joined the enterprise, you must have received the appointment letter. Is the organisation that issued you the appointment letter and the experience letter the same? If it is the same, then it is no problem.
Secondly, did the organisation issue you the monthly salary slips? If yes, then validate the last three months' salary slips.
However, the question arises is why did the organisation issue the salary in cash? What was the hold-up in doing online funds transfer? You need to have a credible reply to this question.
From India, Bangalore
These are normally in cases of proprietorship firms, law firms or advocates.
From India, New Delhi