"
I'm at a payphone trying to call home
All of my change I spent on you
Where have the times gone?
Baby it's all wrong
Where are the plans we made for two
It's not actually about money, the word "change" is a figurative substitute for his real feeling of giving all of his love to her and being left with nothing. Furthermore, the "payphone" is a representative of him trying to get back to his old self before the incident with the girl. Finally, he is saying that she has betrayed him by abandoning the promises that they made to each other.