I had this problem too where RCS suddenly quit working. I tried the do the google way to solve the issue as was suggested above but the options given in the directions weren't even showing up. Retry wasn't an option but ultimately, rebooting my pho...
I did this when I was a new member and was POed because you would think they would prorate but they don't. I went online to chat with an agent and after hours of back and forth...yes, hours...they credited my account as a one time we'll be nice to yo...