Medlife — unable to refund or refunded amount is lesser

I placed an order with medlife, after 3 days i got a message saying one of the medicine is not available. I said okay in this case process other medicines. As i have already paid all of payable amount (Rs 776/-) as invoice was generated for the same. At later stage i have received a refund of only rs 15/ whereas the refunded amount should be approx 75 rs. I tried calling customer care, very rude behaviour the customer care executive was having, he said amount got changed that's why i am getting only 15 rs. Question is if the invoice was already generated then why this changed again. Even i tried requesting executive to give phone to any senior person he denied. Requested for having complain on same he said no complain can be taken or medlife does not have this facility. Anything cannot be done. Order number - or9333co-005a