Perhaps Xnet should make users aware of this number portability transfer fee. The Help Desk should have mentioned it when I first set up the account. It could be mentioned in the FAQ's Question "Can I keep my existing phone number when transferring to the VFX service?" and mentioned elsewhere too. (If it is clearly mentioned on the website please let me know where.)
Xnet should be upfront about the Number Portability fee, it should not be a hidden surprise.