Myntra.com — Error coming when choose a new item in exchange

I bought Hush puppies brown men shoes which i was trying to exchange by choosing option of choose a new item in exchange but everytime error us coming . I am able to do exchange for new request for other items i bought recently accept this product name hush puppies men gormal shoes . So only this product has issue so need help.

I complained but no one is helping me in exchange . They r telling me to exchange it for new size but i want to do exchange for new item as this option is showing but whike processing error is coming

My email id is - [protected]@gmail.com