Big Bazaar - Terms and conditions

My friend and i have installed future pay wallet yesturday ie; **-**-**** around at **:** pm we both got coupans at future pay wallet. My friend went to shoping at **:** am today ie;**-**-**** he has redeemed his coupan on purchase of rupees less than ***,but when i went to shpoing at * pm and made bill of rupees *** they are saying that you should make minimum bill of rupees *** then we can redeem that coupan, then i made call to future pay wallet costumer Care number they said to give phone to help desk number then they made conversation and the helpdesk person cut the call with my permission and saying that you cannot redeem that coupan,then i talk to the manager of bigbazar at phone call he said that you cannot use that coupan that coupan had expired yesturday it self, each person is saying different reasons,then i made call to big bazar costumer care service the person is making fun of the costumer by talking in different manner and he is not answering what the costumer is saying, he is talking what is want to talk and not listining or giving proper ansewr to costumer.