Benze Vaccations Club — misselling

I've been offered a life time membership card of this club for inr10000/- as i refused to pay they convinced me to pay by the installment option of inr2500 for four months. I paid first installment and i got a acknowledgement but there was no acknowledgment for my second payment till now. Yesterday i paid inr5000/- to complete the payment. After receiving the amount they told that the membership price has increased as inr15000/- so i need to pay inr500/- extra there was no prior intimation that they gonna increase the charge and even there was not at all fallow back after my second installment the reason they are saying for that was the telecaller who (Don't want to use the name) spoke with me was not there for a long so a new person (Don't want to use the name) speak with me that i have to pay inr5000/-. Finally i no more want your membership please refund me the money with in a week. I can't wait two months for your convenience as the person asked so.