Manfrotto 128RC Head stuck on Benro Tripod :( Please help remove...

Unfortunately I have been unable to remove my Manfrotto 128RC head from my Benro tripod.
Despite removing the 3 screws underneath the head and tightening the tension bolt, when I rotate the head (anti-clockwise ofcourse) requiring some force, it just seems to turn slowly in it's position without undoing itself.
Any recommendations as to what I should do? Your help would be greatly appreciated, thank you.

Sounds like you need to tighten everything down and use a strap wrench around the part of the head nearest to the tripod base. The strap wrench will give you more leverage. I use the little one from Sears.