Delay in sending picture text messages

I have the Motorola z3 it takes me 15 - 20 minutes per picture if I send text on average. Took 30 minutes the other day.  Wifi does not help.  Small file sizes do not help.  Been 15 minutes now for a simple text message that simply said "thank you: to be sent.  This is ridiculous.  Nothing against T mobile support but this is not an isolated incident.  I am seriously thinking of switching carriers as this is a never ending story every single day it seems although it does not happen all the time it happens every day more than once a day. My data usage is less than 4 GB so I should NOT be getting throttled.  At first I thought it was my phone but 2 other people I know have the same issue.  Now I get a message that the text could not be sent try again - this happens alot as well.  I really like Tmobile but this is not working out!!!