OneNumber for iPhone and Apple Watch

Please please somebody help me who actually knows what they’re doing.

I have a data contract with Vodacom on my phone. I bought a cellular enabled Apple Watch however the ‘mobile data’ menu is greyed out. Apparently something needs to be activated on Vodacom’s side. Your staff in your stores don’t understand it. People in your call centre don’t seem to understand it either. Surely this could be made easier?

I’ve spent an afternoon at two Vodacom stores. My issue has been logged with the technical department and it’s been a week or so.