DO NOT lever the mast between two posts and attempt to straighten from one end as this will almost certainly result in an unreparable kink at one of the supports.
The mast may be straightened by supporting it on trestles, tyres or sandbags or something equally soft about 3m apart equally spaced either side of the point of maximum bend. Then with the help of a colleague or two, ease the mast down in the opposite direction of the bend - the mast will be "springy" and it takes a bit of effort to push the bend out.
If in doubt contact one of our resellers for advice.