Best site to download mobile series is fztvseries. You can download almost all the series on the site. And if you are using Uc Mini browser from Android you can even stream it.
Another option is a site called o2tvseries which has a limited collection but better downloading speeds and faster updates.
All episodes are around 60MB files and have an almost good video and audio clarity for viewing on a mobile.
For another option of 200MB episodes check this out.