Consumer New Zealand is concerned about how many people are paying too much for their mobile phone plans

The Commerce Commission has found a quarter are spending 12 dollars more a month than they need - with some residential customers paying nearly 50 dollars too much.

Consumer NZ chief executive Jon Duffy says these figures aren't surprising.

He says the way telcos advertise their plans, makes it difficult for customers to make a clear choice, resulting in them staying with their original plan and being overcharged.