Grofers India Pvt Ltd - Not refunding the full amount

I have ordered an Oil Jar of *L of rupees *** and the offer contained "free" *L pouch of oil with the original offer (attaching the snapshot).
Initially, I consumed pouch and then opened the jar, whose quality was bad so initiated the return/refund request. Initially, the company refused to take return saying the jar is open. Then somehow I convince them that quality can only be checked after opening. Then even after getting return company did not initiate the refund. After waiting for days and multiple emails company initiated the refund in my bank account which was only of amount rupees ***. They have deducted the money for the *L free pouch. After calculating, I found it was ** rupees less than the actual calculation. And now they are saying they will put money in my grofers wallet. Now I have two complains :

*) how and why I can be charged for the free item, which was not the original product but a free. So I need a full amount.
*) I want my full money refund in my bank account, not in their company wallet.
*) Why I must not get compensation for such insulting and harassing behaviour.