Flipkart refund issue- Can someone help?

Last to last week I ordered a Samsung S24 from Flipkart. After delivery found that the speaker was not working properly and requested a replacement. They were unwilling to give a replacement even though product was still on the 7 days replacement period. They asked to contact the Samsung customer service and get the phone checked as per company policy. After contacting the Samsung customer service, they accepted the product issue and told they can only give a return. The return request was placed and I gave the return method to be crediting the bank account. Now they have issued gift vouchers on the whole amount and not willing to credit the amount to bank account. Tried several times talking with the customer care executive all for them to say the same thing again and again. What should I do next? ( I bought the phone on emi as well)