Loop Mobile — Port out Issue

Address:

Mumbai Suburban, Maharashtra

Hi,
I am using Loop mobile(Dus ka Gang) since last three years. Now i want to change my service provider and so i asked loop mobile to port me out from their network. When i called them, they said that i have to be in their 'Base Plan' for 90 days. I don't understand why do i have to be in base plan for 90 days before i can move out?
I am not changing the operator when i am coming to Base Plan, i am just changing my plan, i should be allowed to port out immediately without any compulsory period. And it should be applicable even if i am using Dus ka Gang.
I have never signed any contract stating this new rule and if this rule is applicable then this should not be applicable for old user and only be applicable who are taking new connection.

Can you please look into this matter and let me know what should i do?