Why charging me more money

Good morning I requested taxify from were I’m working to were im stying, my problem is I used my bank card and the 50% off, the estimated price was R89-R115 after discount, so when I got home I received bank notification of 115 I had no problem with that two hours later another notification bolt took 170 and this morning they returned 115 and they were supposed to return 170, normally I pay 180 if there is a traffic 150 if there is no traffic what surprised me is the took 170 even though I used 50% off I need my money their service is very poor