Complain regarding incorrect product delivery

I am writing to express my dissatisfaction with the recent delivery I received from your company. On 07.07.2024 I placed order for a Samsung M33 5G 6/128GB Emerald Brown mobile phone from your website. However, when the package arrived, the item inside was not the one I had ordered.
Instead of receiving the afore said Mobille that I had selected and paid for, I was delivered a different colour (Green Color instead of Brown).This is completely unacceptable and not the product I had intended to purchase.
I am very disappointed with this experience, as I had placed the order with the expectation of receiving the specific item I had chosen. The incorrect delivery has caused me significant inconvenience, as I now need to go through the process of returning the wrong item and waiting for the correct product. I already been contacted customer service and told them to resolve this issue by arranging a return pickup of the incorrect item at your earliest convenience.They picked up and confirm me that i will received my product before 11.07.2024. But till now I have not received my product. Such a bad and unaccepted service i received from Flipkart.
I expect a full refund for the order amount, as well as any shipping charges I incurred.
Please provide me with a return authorization number and further instructions on how to facilitate this return.
I hope you will address this matter urgently. I look forward to hearing from you at the earliest.
Thanks and Regards Md Ziauddin .