Incorrect notifications

I check my balances regularly, especially when it come to data and buy bundles when necessary. On Wed (22/7) the notification said 1586Mb, Thurs(23/7) 1012Mb, Fri (24/7) 1011Mb, Sun (26/7) 1010Mb BUT on Mon (27/7) they showed 0Mb but 1009Mb Night Owl where it previously didn't show night owl. I was also never sent a notification via SMS informing me that my data had expired. I mention only these dates as I still have those messages on my phone as proof, but do not know how long this problem was occuring. It can clearly be seen that Vodacom confused the actual data with night owl and has now sent me a bill of over R2000 for something that is not my fault as the incorrect balances were provided to me by Vodacom. I have reported this to vodacom as soon as it came to my attention however they only offered me a \payment plan"and did not seem willing to correct this. I do not feel that I should be forced to pay a bill almost 4 times my usual bill because Vodacom provided me the wrong information and failed to send me a notification that my data was expiring. I have sent screen shots of these balances to Vodacom and willing to send it to the correct person again in order to resolve this."""