They have a very strong caching, so sometimes the displayed number of WOFs available could not be the real one (they do not show a newly added WOFs).
If you buy/convert your RPs into WOF (action you may make once per day and where number of possible WOFs depends on your wagering), after conversion  the page with all your available WOFs is displayed. So in the worst case, if you do not see link on the main page (because maybe you closed it with 'x'), you may always got to Rewards page and convert some RPs (50 nowadays) to have the page with WOFs opened.