Vodacom locking calls with positive airtime balance

Even with a positive airtime balance Vodacom locks outgoing calls. tried their stupid app to resolve this but their bot Tobi hasnt learnt this yet. Even called their 135 number and after 4 attempts guess what, when they say a consultant will call, ITS TOBI! ever since the national data limit sms's were received my calls have been blocked despite having a positive airtime balance.