Unethical pricing

I returned home a couple of weeks ago from volunteering with GVI. I found out within a few days of me starting that they charge different amounts depending on where you live. For example I live in the USA and they charged me about $700/$800 more than somebody living in the UK. I confronted GVI with this unethical way of doing business during my exit interview and have had two more conversations about this appalling way of doing business upon my return. They are so concerned about the culture and habits in the countries they have their volunteer opportunities and educate and stress with the volunteers how important it is that we do not offend anybody because GVI wants to uphold their name to high standards. But than they turn around and treat their volunteers in a disrespectful way by charging them different prices for the same thing depending on where you live. Shame on you GVI....Your volunteers are the backbone of keeping your business going. If you do not treat them right than it is just a matter of time your business will fail. A very unacceptable way of doing business.