Unexplainable bank charges

I use to receive my salary through them, 3 months back decided to stop after receiving an sms claiming I owe them R4000.00 when enquiring about the amount I was told it's bank charges. Two months later it was R1000, today I am receiving another sms that I owe them R2000.

I am not paying a cent. Close the account if you must I will not be using Absa.

Thanks