New Xfinity Mobile User - Terrible Customer Service and phone service

I ported my iPhone number from TMobile to Xfinity Mobile on June 23, and ever since I am unable to text Android users. I can voice call them but I cannot MMS text to them. Android users can send me texts to my phone, but I cannot send Android users texts!  I have been in contact with Customer Service almost every week since, if not daily, and am told the problem is fixed but it never is. Today I was on the phone and in live chat as well, for FIVE HOURS and went through as many CSRs all with different names. I told them they hadn't provisioned my account for MMS messaging, otherwise why can I not text to Android users on my iPhone? We did various troubleshooting, resetting Network Settings (twice), checking my iPhone settings. MMS messaging had disappeared but I reset ALL of my phone's setting so that I could get that back which I did, but I still cannot send MMS texts to Android users! 

No one can tell me why this is happening, nor fix it??? I'm about ready to cancel and refuse payment, and return to TMobile, but I thought I would try posting here to get competent help of which I have none, to date!