Finally some good news: the Pre-Termination Fee (PTF) for my SmartBro WiMax has been waived! After almost a two-month wait, I can have it disconnected for good without worries. And they have also submitted a request for Monthly Service Fee (MSF) reversal - which I actually don't need, but thanks anyway. :)
I would like to thank Angie (she didn't give me her surname) from Customer Care for handling my request.