Aldo shoes - Denial to provide purchased product

I had purchased a pair of shoes, original MRP INR *****, under an offer where the price was INR ****. The Aldo warehouse shipped an incorrect product. When I requested an exchange with the correct item, they said they cannot exchange. They said they’ll process a return and I will need to make a fresh purchase. By then the offer had expired and I was required to buy the pair at original MRP. I requested them to honour the offer as the error was on their part not mine and I shouldn’t have to bear the consequences. However, they denied and asked me to make the purchase at full price. They haven’t yet processed a return or given me a refund for the incorrect item so in total, I have lost INR **** already, and will have to pay an additional INR *****, if I do want the item that I have technically already purchased!