From your latest post it is evident that you were in the services of the MTC from 2006 to 2017 till September and resigned your job.
However, in the meantime when the new company styled as "Imperial" was formed either by MTC or by it's directors or owners as the case be, you were asked to look after the accounts of MTC and you also did so as an employee of Imperial effective from 2010.
Obviously as per the oral instructions of the persons who happened to be the directors or partners of both the companies, your salary for the period from July,2012 to April, 2014 was debited to the newly formed company's accounts.
Though as the Accounts Head for both the companies, you were aware of it, you didn't raise any objections to such practice that continued only up to April,2014 for the probable reason that you lightly took it as a matter of book adjustment without any formal orders of transfer of your services or any inter-company note.
From May 2014 up to September,2017 your salary was paid again from the old company. And you put down the papers in September,2017 due to the grievance you just mentioned.
Therefore, you had been in the employment of MTC continuously without any formal/official break and rendered a continuous service of 11 years.
You send a formal notice to MTC claiming gratuity for the entire period of your service and await its response. Later you can file your claim for gratuity depending on their response.