Update to 8.3 ca't get yahoo mail but can get gmail and outlook

Recently updated to iOS 8.3 on iPhone and iPad. Can't get 2 yahoo mail accounts. Error message can't access server. Worked with 3 different support over phone - deleted/added both yahoo accounts multiple times. Support suggested 8.3 didn't installed correctly eventho installed withitunes. Support helped to reinstall 8.3 and my apps and data. Support supposed to call back after each session and never did. Was sending me articles to explain and never did. Support said can't go back to 8.2 where there were no problems.