how much refrigerant is needed to replace with R-134A on a 2014 Toyota Tacoma

Hello, the capacity of the air conditioning system is 20-22 ounces of refrigerant. How much you actually needed is unknown, and the cost per ounce is unknown. And more importantly -- why did it need the refrigerant? It has to have leaked out; it's not consumable like a fuel or something like that. The big concern here is that without repairing anything and just charging the system, they haven't done anything that will be a sustainable repair.

This question is best address to the appropriate personnel at the facility that performed the work. We have no ides exactly what was done.