How to cancel unused Prepaid plan Add-Ons
I have a Prepaid plan account. I accidentally bought an International Travel (Roaming) Add-One that I don't use. I haven't used the Add-On (I've never been to countries where prepaid roaming is supported since I bought it). The Add-On has not expired yet, but it'll expire in a few days.
Is there a way to cancel the Add-On?