Vodacom data contract won’t even make WhatsApp calls

I have got a data sim contract for my wife for the past 2 years and it has not been able to switch to 4G. It just stays on 3G and is unable to even make WhatsApp calls. I have gone to the vodacom store multiple times and they don’t know what’s wrong. Sim swap was done. Phone was changed. Call center has escalated the matter with a time frame of 7 days to resolve the matter. This time has passed and nobody has gotten back to us.