Mediator is arguing rent was not paid for last month.

My relative is tenant in Bangalore and signed on rental agreement with owner(stays in other city).Mediator is taking monthly rent from my relative by cash only and not willing to take rent by bank cheque/online. Relative asked mediator about owner mobile number, to inform owner that he is vacating house(2 months notice period), but mediator refused to give owner number and arguing that it is his own house. Relative is paying rent to mediator by cash for every month, with in first 5 days of the same month. The mediator is saying that he didn't gave last month rent and asking proof for paid rent. The mediator is arguing that everyone in Bangalore will pay rent after completion of the month.(Example: for April month rent, relative gave cash on 4th-April. But mediator arguing that rent paid in April month belongs to March and saying April month rent is pending). Rental agreement is written as follows: RENT: The monthly rent payable by the Lessees to the Lessor for the schedule Premises shall be of Rs8500/- (Rupees Eight thousand five hundred only) per month.This amount shall be payable before 5th day of the month. Questions: 1. What is meant by "This amount shall be payable before 5th day of THE MONTH". Will this statement prove that my relative paid rent for April month? 2. How can my relative get house owner mobile number? 3. My relative didn't aware of doing renewal of rental agreement. This rental agreement was already expired by end of last year,but my relative has gas and electricity bills paid after the expiry period. 4. Can he file legal case in this situation on mediator? If YES, what type of case can be filed? Need your valuable suggestions on this.