Day light *******

What a ****en ****!!!! When I booked our tickets today around 13h30 it showed that the ticket was R1100 from CPT to Bloem, then the system kicked me out as I am inputting my family details... when i went back in, it was R1400. When I added the details of my family if 4(including an infant) the total came to R5900. Now when phoning the airline, asking why my infant had to pay full price, the lady is telling me I booked the ticket at 1800. And I am telling her that is absolute bull****!!! I would've never booked for that price. But clearly she wasn't interested in assisting me!!!!!!!!!!