CraftsVilla — Fraud- Once paid for the item, asking for more money

Hi, Thanks in advance. I bought a pair of anklets from the website which were listed for rs 1650. I paid the amount in full have I was promised to get the item delivered ASAP.it was a gift for someone, and after few days they asked me to pay more as the item was worth rs 4350. they said it was mistakenly put as lesser amount and asked me to pay the rest of the amount before delivering the gift. instead of returning my money they are asking me to accept a voucher from their website which i really do not want as its a clear case of fraud as they wanted to fetch some more money.When they promised to send the item and deducted the amount from my account i believe they should deliver the item as well or pay my money+the fine for wasting so much of time time+spoiling the gift to someone special. I will really appreciate if you could help me