Data Vanished in thin air without a trace

I am on pay as you use data agreement which is R50 per 1GB .. from September 2019 i have been using max 5GB & which amounts to R250,on occasions i would increase by 1GB. Since Tuesday last week i exceeded the 5GB ,added 1GB it vanished same day,added again the following day with 1GB & it vanished again..i stopped using it bought 1GB Vodacom data that lasted me 4days..Today at 7am i added 2GB again on rain data in less that 2hours it was depleted. I contacted them immediately on Facebook chat which the normally respond swiftly on queries, send them an email & dololo response since morning. I am suddenly not impressed