It would have been cheaper to not use kulula or the discovery vitality discount

We rented a car earlier this month through the Kulula.com website and I used my discovery vitality discount. When I booked the car originally I did so as I thought it was the cheapest. I noticed that there was no option for unlimited millage so I just assumed it was something that I added on when we collect the car, as I had not remembered seeing this option when getting quotes from other websites. When we collected the car I asked if we could add this to our bill to which the response was no and I was told (incorrectly) that we had to pre organise that with discovery vitality. I then called discovery vitality and was told that they do not handle those bookings and that I need to call Kulula.com which I then did. When I eventually got through I was told that they do not offer that option. This is something that I should have been made aware of when making my booking. I would have gone directly through the car rental company. But I could not cancel my booking since we needed a car, had already been there for well over 20 minutes trying to sort this out and didn't really know what other options we had. When my boyfriend received the final bill we were horrified! Nearly R5000. Over R2000 was due to the millage. All I can say is don't use it unless you can be sure that it is worth it. It is not worth the +/- R400 (incl vat) discount you get. Is it even a real discount? Our daily millage was only 100 km per day. If you driving really short distances that is fine but if you planning on driving from the airport to Pretoria and back with a stop off at the shop you will probably end up going over super easily. It is ridiculous. In the past we have always been given 200 km free per day from other companies. I understand that we did go well over our allotted distance but what upset me is that we felt trapped. We asked for unlimited millage and we could not get it. The staff who were friendly, should have also known that it is not an option instead of me having to spend a fortune of airtime on two phone calls. On top of all of this the windscreen had cracks in it. If those cracks had grown would we have been charged for that too? I now know that I need to be very cautious using any discount offered through this website in the future and I would recommend others are too.