Payment for E-toll SANRAL ripoff.

I am highly upset as I recieved a letter today in the post from SANREL for E-toll and in the letter the letter invoice is dated 2019/10/18 and at the bottom of the invoice it gives a discounted rate to be paid before the date which was yesterday the 17/11/2019. I feel that this is a way of them making money from the community by having it delivered late in order to pay that extra %vat.