What should be the format of application to change from bsnl Home 250 to 500c

i have already home 250 plan but i want to change it to 500c.
please tell me what should be the format for application and what details should i give in application??

Kammy , I mentioned that earlier too.
Here : Procedure to shift in plan in BSNL

It is simple, just write simple application and thats it.

Thanks for procedure butplease tell me details that should be mentioned in application.

i have already home 750 plan but i want to change it to 250.
please tell me what should be the format for application and what details should i give in application??

There is no specific format . Simply write a plan application requesting to change in plan, deposit it to bsnl office nearby along with copy of your latest paid bill. And you are done. They will change your plan by 1st of consecutive month.