XFINITY wifi says "invalid credentials" whyyyy???

Help! On my phone I have tried deleting the network, then adding it again, tried messi g with the settings there too. Nothing. Still invalid credentials. Tried changing my password, nothing. I have tried everything i can think of, I'm certain it's not an invalid password. So whats the problem? I need to be able to use this XFINITY wifi network!! Oh, also have tried deleting and reinstalling the wifi app. Nothing. Can anyone, ahem comcasssssst!!, help me get back onto this network I was.previously able to jump on with no issues and the username and password I have had and changed and I know is all correct? Whats the real issue and fix it!!!!!