Servicing at Hyundai they will ***** your petrol

I took my ix 35 for a service on the 4th April 2018.I usually don't fill up my tank when I take my car because of previous experience. On the day I had 98 km to still but decide to fill up for R200 BUCKS I HAD SOMEWHERE TO RUSH TO LATER ON.I made a mental note that when I dropped off the car it had 238 km still to go. Picked up the car just before they closed around 16:50 or so. Get in the car just drove off got to the robots realised the petrol sign was on and indicated not a drop of petrol left. Luckily for me the corner I was at had a Caltex so managed to fill up. Was fuming called Hyundai the following morning manager tells me its definitely the sensor which was not replaced properly, took it back Monday the 9th 30 minutes after dropping the car they called to say its sorted. Guess what the petrol gauge did not move an inch which I am assuming should have been the case after sorting out the sensor.