2006 td4 top belt tensioner

Hi folks just joined landyzone, got a problem, went to change serpentine belt used a 24mm ring spanner turning anti clock the hexagon just keeps turning but the tensioner does not slacken off, my haynes book calls the hexagon a bolt but it looks like a nut, in the center is a threaded hole looks like rt hand thread?, is something missing out of the thread or do i need a new tensioner, this is the first time this job as been attempted on my car i think a nother member else has had this prob in the past thanks in anticipation.

I am presuming you have a Freelander so you may find you get more response if you post in the dedicated "Freelander" section.
There is also a bit of a protocol on here that you go to the "introduce yourself" section before asking questions.
It may be worth trying a search in the box above next to your name as it is likely that somebody will have posted on this before.
Oh and :welcome2: