Is it possible to receive refunds for online purchases to a Thomas Cook foreign exchange card?

What you have is usually called a pre-paid credit card. You pay some money (Indian Rupees) to the credit card company, and then you can use the card to pay for purchases etc in foreign (non-Indian) currencies upto the remaining balance on the card. If a proposed charge exceeds the remaining balance, the transaction will be declined when you try to use the card.

There might be multiple ways that the card is set up, e.g. it might be restricted to charge purchases denominated in US dollars alone, or you might be able to use it anywhere in the world (except India). The balance on the card might be denominated in INR, or in US$, say. In the latter case, the exchange rate at which your INR payment was converted into the $US balance is fixed and agreed to at the time of the original payment: you paid INR 70K (say) and the balance was set to US$ 1000 even though the exchange rate on the open market would have given you a few more US dollars. In the former case with the balance denominated in INR, a charge of US$ 100, say, would be converted to INR at a fixed agreed-upon rate, or at the current exchange rate that the Visa or MasterCard network is using, plus (typically) a 3% fee currency exchange fee, and your balance in INR will decrease accordingly.

With all that as prologue, if you made a purchase from Walmart USA and later returned it for a credit, it should increase your credit card balance appropriately. You may be whacked with currency conversion fees along the way depending on how your card is set up, but with a US$-denominated card, a credit of US$100 should increase your card balance by US$100. So, that $US 100 can be spent on something else instead.

In short, the card is your "bank" account. You cannot spend more than the remaining balance on the card just like you cannot withdraw more money from your bank account than you have in the account, and you can recharge your card by making more INR payments into it so as to increase the available balance. But it is like a current account in that you are unlikely to earn interest on the balance the way you do with a savings account.

So what if you are back in India and have no further use of this card? Can you get your balance back as cash or deposit into your regular bank account? Call the Customer Help line, or read the card agreement you signed.