reply letter

One of our client received demand notice( date mentioned in letter 11th jan 2018) for non payment of PT for previous 5 years, actually the client stopped the in the same year of commencement due to heavy loss, not even taken registration for running business but still received notice of demad under employment act but he has submitted application under sec 5 of employment act ,notice mentioned that personal hearing on jan 22nd 2018 but they received letter on 27th March 2018.
how can I go ahead ....pls any one guide me.

Thanks in advance
Tanuja