How can same trip cost R130 more!

Last night ubered to and from same address. Driver 1 asked which route he should use. We said which ever was recommended by his gps. He used highway and we arrived 30 mins later at distance of 30 km. I had enquired for fare estimate before and got quoted in range of R170. Got out and saw trip was R188 not realizing R100 discount I had available had already been app**** or I would have queried. Imagine surprises when realize trip was R288 and discount had already been app****! Car had terrible smell. We had to ask driver to turn down radio. We were not asked any of std questions about temperature etc. <br> On way home driver 2 completes same trip via different route as per his Gps. Route 2 is reportedly 16 km and takes same time yet it only costs R150. Driver 2 asked what radio we want, if temperature is good etc. fare estimation was R140 before trip so it was within reasonable range. <br> <br> I find this completely unacceptable. It is not up to me to look at routes before and work out distances and then guide driver. I find the cost of the first trip unacceptable and want to know what my opinions as a customer are. Happy to provide both driver details. Fare estimate completely different.