wasted my time

We just come home from grocery shopping at Wall Mart. I am very upset the line at the register was too long. I mean I was okay with that, I know because it is Sunday. But the woman behind the register is very slow I was there standing in line for almost an hour. When I checked my receipt she charged me for 5 gallons of nursery water and I got only four. I complained I know that for only $1.18 I am not supposed to complain when the line is so long. But I had already there for almost an hour. The people behind me started complaining and some had already transferred to other registers. Even my son was bored and started to complain. I cannot understand why the lady at the register was so slow. I told my husband that next time before I go in the line I will check the cashier first if she is fast or slow to make sure it will not happen again. I wasted my time in the line while my children are waiting for me to come home.