Jet Airways — Cheating customer

Address:

Thrissur, Kerala, 680665

Am mirthas akbar and i booked a ticket on jet airways on coming 29th. I payed a amount of 7900rs for the ticket when i am asking for cancellations they told to give a refund of 300rs. Then i asked i don't want refund i will change my date and fly on july 6th the same flight costing rs 6200 in their site when i ask for a date change to 6th still they asking to pay a amount of 6100 then what the use of date change. Please help me with this issue.