att.net yahoo mail has many anomalies since upgrade

Since the recent 12/13 upgrade, the yahoo mail site has not been the same.  At times can't delete mail, after reading email, click on inbox and are immediately returned to home page not inbox.  Did online chat support and it was fixed about 8 days ago but now it's doing the same things over and over again.  Very frustrating.  When is this problem going to be fixed.