Dar gato por liebre
Meanings of "Dar gato por liebre"
Literally means they give you a cat for a hare. When you're given something worth less than what you think you're being given.
Engañar en la calidad de una cosa por otra inferior que se le parece.
To deceive in the value of something with something else, inferior, that appear to be similar.
(I am trying to find something 'similar', of the same value, in English).