my opinion on your queries are as under
1. Who can file suit on the customer on behalf of the company.
Opinion: any person appointed by company via POA can file the complaint or suit on behalf of the company.
2. If physical presence of the person filing suit is compulsory on each and every date during the proceedings of the case in the court.
Opinion: yes it is mandatory but if there is any advocate then no need to worry the advocate can handle the case.
3. if the person on whose behalf suit was filed left the company, can company appoint any other person to be present and represent the company in the court.
Opinion: yes the company may appoint any other person to represent or fight the case on behalf of the company.
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