Airtel — prepaid to postpaid family offer, waiver for the child number

Address: 560076

[protected] (Parent), [protected] and [protected] (Child)
All the above mobile nos. Were on prepaid for more than 10 years.
Airtel office at bannerghetta road bangalore offered me post paid offer
Converting from prepaid to post paid where in child no. Will get waiver monthly charges. But so far, i have to fight for this waiver every month.
Fed up with the customer services i have opted revert back to prepaid connections for which airtel is demanding me to furnish the mandatory documents for this i am refusing. Previously i have submitted all the relevant documents may be umpteen number times. Why should i submit / furnish just for go back to the same scheme. Where are my documents previously furnished.
Airtel do not give timely connections, harassing customer like me.