Vodacom ********** data contract

Im paying 199 per month for 20 gig of data, however I believe there is a huge ********** activity going on behind the scenes thats making data misteriously dissappear. My vodacom app details the total data used for my Sim for the period 20May2020 - 18June2020 is 9gig, which makes no sense because every 1st of the month I receive 20 gig of data and the funny thing is that between the 15 to 16 June 2020, I received an sms telling me my data is on 700mb, normally in the middle of the month my data is abt 10 gig, and I did not receive any sms when my data was on 10 gig. And now the funny thing is that my night surfer was left with 20 gig for the current month and 8 gig for the previous month, however it has misteriously disappeared and now for night surfer I only have 19 gig. I called and complained and was given two 5 gigs which is 10 gig and no explanation whatsoever, I believe they were trying to make me quite by giving me two 5 gig after complaining. Vodacom is **********ly depriving me of the service i pay every month.