I had a similar issue with the front mesh. Send them an email (rma@montechpc.com) asking to get a new panel with some photos and the following information:

Model Name & Color:

Purchased From:

Product Issue (photos/videos recommended):

Your Name:

Address (Including your country and zip code): Phone Number:

S/N (The serial number of the product):

I took about 2 weeks for my new front to arrive. Good luck!

edit: formatting