SEO Friendly URL - Forbidden Error

Hi,

Whenever I type a SEO Friendly URL for that product, when I save it I get a Forbidden error.

My htaccess file can be found here: http://pastebin.com/eRx3KshU
My store URL is here (It's not open or ready, placeholder images currently): https://www.gamingdynamics.com/store/

I use the latest OpenCart and I'm hosted with UK2 which apparently does have mod_rewrite enabled.

If somebody could assist that would be kindly appreciated.

Thank you.

Additional rewrite rules must be placed after RewiteBase string
Not in begin of file, as in your case