Dishonesty and *****

I've recently moved to bloemfontein and have started making use of the Shell in Rockland. The first time this happned I thought something was wrong with my petrol gage. Mind you I only ever encounter this problem when I pay cash. I topped up with R100 to get me throught the week. My gage didnt go up nor my km. When I asked for the lady who serviced me she was nowhere to be found and when I asked for a slip I was given a slip with the wrong time stamp. 15min before I actually fo there! Can you assist. Cause this isn't the 1st time.