L T Online Store Mumbai - Refund is partial

I ordered a vga * meter cable total cost ***/- received the product on **/**/****, but it was defective, on the same day I informed them about the issues and on next day I raise a concern over email, whatsapp and telephonically, they told okay you please return the item, we shall refund you on receipt of item. Next day I parcel it through india post on a cost of **/- paid by me, they received the item on */*/****, but they were totally ignoring me, and every time bringing new excuses for not refunding the payment.after repeated follow up they finally refund me part payment of Rs. ***/- on **/**/****. In this way they are cheating and refusing for the remaining amount. I e mailed them explaining all the events and conversations, they are not replying the mail and telephonically asking for the payment of ***/- to reply e mail.