Data disappearing and escalating bill

Dear Vodacom, Please refer to the call S3-9OF37-7N52O, I tried to buy a 1 Gb bundle but it never app**** to my account, It did show in the total data but was instantly gone as well as my account was billed for and additional almost R2000 which is equal to the out of bundle rates for 1 Gb, it is impossible that I could have used that much data within minutes on my phone. The Call centre lady that contacted me (Nicole) was very helpful and profession, she also added another 500 Mb to assist me, however a day later when I still ha almost 400Mb left the same happened - the data disappeared and another R2000 was added to my bill - Now Almost R5000 in total!!! This is totally unacceptable and there is no way I will pay for data that I have not used. Not to mention the inconvenience.