Urgent

I was attending correspondence with Intec College from 2013 up till I get summons from them that I owe the College R900 , I paid them that amount on 2017 , and I became stunned when I received the SMS from College on the 06 January 2020 that there is no record of payment on my Intec College account and the message stated Legal Notice for the 2017/10/25.

Can I have clarification on this matter, my previous student number with the college is ***.