Day light *******

I have been paying GLA from 2022. I increased the amount I think in August 2022 to R1000 monthly and been paying religiously every month on the 2oth of every month. The first issue is the harassments, even today I got an email to say my payment is late my last payment was on the 20th July. Like really id my debit order is the 20th of everymonth, how is the 16th of August late? second issue, for over 12 months I have been paying R1000, my initial debt was R21 000, but I still owe R14 071 as of today. This doesn't make sense