Hi Sarthak, the purpose behind this strategy can be grasped to some extent, but what made them adopt this modus operandi is unclear. This is an unfair labor practice.
I could guess like this:
1. To deny you the lengthy, continuous service (however, having already served for 6 years, you have become eligible for gratuity, so there is no escape).
2. When you are taken back as a new employee, if at all, they can as well fix your emoluments lower and make you commence your second innings all over again from scratch, denying seniority, etc. So, nothing can be guaranteed right now regarding your future prospects.
3. They will have the freedom to place you anywhere as per their will.
4. They are adopting this route also to avoid payment of retrenchment compensation, etc., if they had to retrench you, instead (cunningly, if I'm right in using this word), asking you to resign. It's immaterial here how many months of notice period.
We are now in November. What have you done since October 31st? Are you working there as a vendor? What's your compensation package then, more or less?
I can only suggest you weigh all options, including what if they don’t take you back with all protection next year. And whether they are paying for the past service. Most probably, you will lose EPF contributions from now until you are taken back as an employee, if they keep their promise at all. Still, the choice is yours; your circumstances will decide on options.
Oral promises are seldom kept.