Mobile Telephone Networks [MTN] South Africa review: data not being loaded correctly

Since April last year, MTN have not loaded my data correctly, as per my contract. I am to receive 1GB + 2GB as per my contract and an additional 2GB as an add on bundle. I have attached the SMS I receive on thec27th of every month, which shows this.
However, I receive 1-2 GB less each month, or they don't honour my carry-over data. I have included a screen shot of the data on the 27th of this month. Only 3GB was loaded (instead of 5) and 800MG was my carry over data.
I have phone 135 Customer Care and received reference numbers, sent messages via messenger and received reference numbers. I then receive notification that it has been resolved, which it is not. Then it repeats the next month. MTN owe me at least 20GB in data which has not been loaded and not carried over. They have not honoured my contract and no one seems to be able to fix it. They can pick up exactly what has been loaded each month, but there is no accountability.

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