Ridiculous overcharge

I use uber 5 times per week . My journey is always 12.2km and approx 120 zar and takes 27 mins. I just had a journey where I was charged x1.7 because it was busy so my bill was 236 zar for the same 12.2km and 37 mins which is only 10 mins extra yet the bill is double the norm. I'm disgusted .