But what if you have a problem with the top-up? Or just a question? Then the specialists at Proximus, Mobistar and BASE are on hand to take your call.
For Proximus: call 6000 or 078 05 60 00.
For Mobistar: call 5100 or 0800 85 007.
For BASE: go to https://www.kpnonline.be/en/prepaid_autoreload_faq.html.