A student has just shown me a wonderful new web site which is completely free. The site is colingo.com and is a forum where teachers who are native speakers conduct online classes on various topics. When you access the website you can see at a glance which lesson is ongoing, which are pending and the past lessons. You can join in at once via google hangout. On the left, you will see the list of teachers. It is a superb site; I loved it and I hope you find it beneficial.