Useless customer care stuff

I paid R300 via EFT to my EDGARS account 01 March 2021,but yesterday they called me saying that I didn't pay my installment for last month and they asked me to send them my prove of payment. After I send them the prove of payment they don't want to us my calls anymore as want to make me the bad payer ****** useless stuff who doesn't care about their clients. My number is *** call me and tell me.