No refund after months of back to back communication

I app**** for a visa renewal for my 2 daughters the 30th of July but used the wrong condition so i had to apply for another renewal which for the 4th of August. I paid 2700 as a single payment in total for both daughters. I then requested for a refund and was refunded 500 only.

I then asked for an explanation for the 500 rand refundand why i could only request for a refund for one child, the second child gave an error that "Refund cannot be initiated for this application, as the payment has lapsed the (6) months period from the date of becoming eligible..." yet i app**** on the same date.

I also i provided all proof that i had reapp**** for the renewal and still I got no explanation as to why i got 500.

The last communication just said you have been paid 500 but no explanation as to why i got 500 and why it gave the other error for an application made on the same day.