Angry customer

They sent me a message saying I own them R1197 in 13.02.2021 on the 25th of the same month I paid 500, in March also I paid R500 again when I check my till slip to my surprise I now owe them R1564 of which raised my suspicion I called them to clear that they told me now is R1789, so which means everytime I their balance increases not decrease this is day light *******, they say I must email them my sms I did but there is no reply or communication