Monte Carlo Fashions Limited - no refund after returning product

I had ordered Women Peach Printed Hooded Full Sleeve Sweatshirt in size S on **th Jan ****, received on **th Jan ****. I found out that it was a misfit and I needed size M. They do not had a exchange procedure so I requested a return on **th itself. I was asked to share product pictures with its original tag intact, which i did and upon their satisfaction It was picked up on **nd Jan ****. Today I have received an email from Monte Karlo stating that the product received is not of Monte Karlo. When I checked the pictures that they shared, to my disbelief, I found out that the pictures sent was of some different product that I sent/purchased. I am pretty sure that Monte Karlo's delivery and pickup partners have done a mistake whether knowingly or unknowingly. I also doubt that Monte Karlo does not want to return the product. I have sent them the product and have also paid them online. Kindly help me resolve this and get my money back.