Payment Query

Have been with Vodacom Fibre for close to 3years now but lately was treated unfairly, since early February they have been sending emails to say I am owing for the month of January which I was 100% sure am not since they debit straight from account. I sent them my bank statement to see that money was debted from my account and the mistake was rectify so I thought but unfortunately nothing was rectified been having the problem since, even now they say am owing R2099 l dont know how because am paying every month