Screen Guards India — i ordered a wrong product. theyre not cancelling my.

Hello
This is yeshwanth
I have ordered apple watch series 4 tempered glass on screenguards.co.in on september 6th.
With the order id #[protected] and paid online. I wanted to cancel order due to screen size (I. E 40mm). I have misplaced the ordered with 44mm. Now, i have requested them to cancel, via mail and also tried to contact them. There’s no response at all from them. Even they haven’t updated my order in my account. Seeking for the help. I am filing a complain against them. Please help me with the issue.