Texting issues, trouble sending

Yes, thank you, after about six calls to T-Mobile customer care, finally one gentleman told me about the RCS needed to be off, I never knew that before and it worked for a week and then the same problem.  I wish that was it.  I reset the WiFI,mobile & Bluetooth reset option every time, I also double check to make sure in case somehow the RCS got turned on, I toggle back and worth in airplane mode and restart my phone.  Then I pray it starts to work again.  After I learned I could send gifs, I'd do that a couple times and once that's what seemed to make it work again is if I sent out a gif first, weird right?  I'm sure that's not it at all and I am missing something.  Thanks for advice.  Your answer for that was much much faster than customer care who I am on hold right now for. LOL