Understanding Probation and Confirmation
There is no deemed confirmation. Though there is no law in support other than an official document like certified Standing Orders of the company, many court rulings support that unless intimated in writing of their confirmation, an employee will continue to be under probation. If you are sure that you were not intimated of the confirmation and have not received any benefits or facilities from the company that are available only to confirmed employees, then only can you start legal proceedings against the company.
My doubt comes from the fact that you have been with the company for the last 2 years and have not taken any initiative to inquire about your status, whether confirmed or still under probation. It may also happen that due to oversight, HR might have missed communicating your confirmation but at the same time put you under confirmed employee status, enabling you to avail benefits or facilities available to confirmed employees. If so, it should only be considered a minor clerical error on the part of the company.
Benefits for Confirmed Employees
Though all statutory contributions and payments like ESI, PF, Bonus, leave with pay, etc., are available to probationers, there are some benefits like advances from the company, leave travel concession, medical facilities to family members (other than that provided by ESIC), and other non-statutory welfare measures, which are available only to confirmed employees. Please check.
Considerations Before Legal Action
Before filing a case against your (past) employer, please understand that you will be wasting your time; obviously, you will have to take leaves very frequently, and you will have to reveal to your present employer that you are fighting a case against your previous employer and the reason is so and so. This information may be irritating for your present employer and may even lead them to think that your probation need not be extended but put an end by giving you a termination letter before you become a confirmed employee!
As already stated, there is no written law on probation and confirmation, and everything depends on the contract of employment or the company's policy. Even the period of probation may be different for two companies. Therefore, take it in good spirit and negotiate with the employer to get relieved. From the information about the salary, it also happens to know that you will not get protection of Labour Laws.
Regards,
Madhu.T.K