Hi! You may find this link useful - almost the same question, asked a few years ago: http://www.italki.com/question/113189

"I have been waitING" with the ing means that you are doing it right now. "I have waited" means that you have already done it. Either right now or last week or a year ago. So you have waited two hours but you can still be waiting.

If you use the time period of a process like " for two hours", you should use "have been doing"