Underscore in Parameters

http://www.hvaitamins.tempurl.co.il/keratin-styling/?single_prod_id=41

Hello, can you please check out the parameters in the above link, they all have an underscore in between each word. I did a search on the support page but all that came up was other people who had this problem and you requested that they email you but your email server rejected my message.

Kind regards,
Boris

https://wordpress.org/plugins/product-catalog/