Unresolved Paid policy

I paid via EFT as usual on the 18 December 2023, on the 30th December 2023 I received a message that I did not pay, I sent to them proof of payment on their WhatsApp number and their email since I couldn't get hold of them on the call the same day. On the 2nd of January 2024 I called and they answered, and the requested that I must email the proof of payment again, and I did. Today, the 7th January 2024 I receive an sms that my two mountains account is in errors. How on earth do I resolve this issue. Talking to them and sending proof of payment isn't enough.