60days trial offer....

I have taken the connection under the 60days of free trial offer.But,they have not mentioned anywhere not in the demand-note that it is free 60days trial offer.Now,i m worried what to do n how can i know after the telephone bill comes..that they charged me a amount or not ??Will they charge Rs500 (250+250) per month or not ???They say that we have records in computers there is no need of mentioning.Anyone has taken this offer may know well to answer.Pls reply me fast.I got the connection on 9th n they show that it started from 6th so how does the calculation of month takes place...