Firstly you will have to serve legal notice asking them to refund the amount paid by you as well as compensate you for the mental agony and harassment suffered by you due to the deficiency of services rendered by them asking them to do the needful, within 15 days of receipt of the legal notice.
If they fail to adhere even after the receipt of the legal notice, you will have to file a complaint against them in consumer court for deficiency of services and unfair trade practices adopted by them under the Consumer Protection act, 1986.