Unprofessional, rude and poor customer service (Dollar Thrifty Car Rental - Sandton Gautrain Hotel Branch

I booked a car online yesterday and paid the full rental amount, the pickup time on the system was 17h:45 as selected, to pick in it at Sandton right opposite the Station at the Gautrain Hotel. I took Gautrain from Midrand to Sandton to get there when I got there it was 17h:10 and everybody was still inside hence I walked in with the expectation that I was going to get the best service that I had been getting for the past 9 years of renting from Thrifty. However, I found a lady, who told me right away that she's the manager and refused to assist me despite having explained to her that I had been calling and stayed online waiting for someone to pick up the phone with no success. The worst part is when I told her that I came from far and I had not budgeted to use Gautrain and a Taxi back home, rudely so she responded in Setswana and said 'Utla dula he' (meaning i'll stay in Sandton because there's nothing that she can do for me. It was the most horrible experience ever, to a point of her suggesting that I cancel the booking, which I did, and now awaiting the refund which she said I'll get in 14 days. I had no choice but to make another booking in Centurion because I am very disappointed with the Manager in Sandton, I don't believe she is competent enough to deal with customers or to even work in the front because she is very rude and unprofessional. It was so distatesful....