Highly disappointed by Shell Jabulani

I've been a loyal customer to Shell garage Jabulani for years now, Yesterday I went to top-up with R100 and I was on 107km and i know its about 4ltrs, but i didn't move so i thought maybe it would move as i drove but it didn't, i was confused because it kept on decreasing as i was driving, when i came back i went straight to the garage because i was now sitting on 22km HOW?????... So when i went back the pump that i used had an orange cone in front of it, which clearly means its not working, how can i have 107km poor R100 and it doesn't increase the km's instead it went down, i feel like the was a problem with the pump or i was ****med, im very disappointed because i always recieve great service from the guys working there .... Well Shell just lost a loyal customer because im never going back there ever again.