With regards to the bonus month issue... i don't think so. Singtel's profit from the local market is roughly ard 20 odd% and the internet sector is quite minor as compared to the mobile/home/commercial phone market.
Anyway, i think the practice of prepaid service as compared to post paid service is ong overdue.. i guess with the current unlimited surfacing packages, there's no reason for them to wait till the end of a period before billing. Technically, there are no excess charges so it would be easier for the accounting as well. Also, maybe we have to thank those who surf n yet don't pay their bills that probably constitutes to this change.. haha :P
Anyway, the above jus represents my pt of view.. not a singtel staff or watsoever.. a singtel user though