Bad Service

I had purchased pre-paid electricity from them on the July 1st, now I was busy moving and had a work function i gave the cashier the card with the meter number and the consultant punched in the wrong number, I went back on the 8th as soon as I got back, and there was a coloured lady who was so rude telling me I have to remember the cashier, I mean do you always remember the cashier you buy from??? I think it's a stupid policy and there was so much attitude when they assisted me.