money taken for services not provided

I bought 5gig telkom data using absa cellphone banking. R300 was debited from my account immediately but I never received the data. Went to Absa bank and they said they couldn't help and that I needed to go to telkom. so I went to a telkom branch and they say don't evidence of me purchasing the data and it the banks fault and i need to go the bank. what does one do in this situation, neither of these service providers want to take responsibility but my money is gone. very disappointed in the service