Hi Muzdaz,
I said wrong because they can't buy 3/8s of the stock on the market at one go. They will have to do it in 3% tranches every 6 months, and not necessarily above the $22.15 offer price. 6 months is a long, long time in the market.
The other scenario is they make another proportional offer which Hotcopter has kindly pointed out would need to be made at least six months later.