Macbook charger isn't working
Is your MacBook charging up properly when you are using it with the charger plugged in?

It might only be drawing 12W of power because your batteries are fully charged and the 12W is only used for your current operation.

Having a charger capable of giving 60W does not mean your MacBook will always require 60W from it.

For example, my MacBook Pro is currently drawing 20.31 V from the power adapter right now.