Daisychain,
The online payment system is still on Beta stage, they can close it anytime they wish for, that's the reason they (customer representatives) discourage using online payment, though we all are looking for shortcuts, so we do risk that factor.
And I really am not sure why the morning customer care representatives don't give out the IIN, but it has happened to several of VJ posters where they could only get hold of IIN at evening hours, it has been the same with me too, my husband was trying to get the IIN for 2 days and finally got it through a few days ago.
Wish you all the best