Not receiving sms texts till hours after I've sent them! Receive the replies in a bulk with time I was supposed to receive them next to the message. Tried resetting everything, network the phone the lot. Turned off and on, turned iMessage off? HELP

a pop up on my phone came up yesterday just like it would when due an update saying I could update my cellular network signal.. So obviously I pressed yes. And ever since i have not been receiving sms messages the time I was supposed to. I would sent an sms & hours later receive the reply with the time it was supposed to be received next to me.. Majority of the time it would say received 2 minutes after I'd sent my text. Yet I'm getting it hours later?? I have reset my network several times, reset my phone settings, turned iMessage off, tried turning my phone off for a long period of time and turned it back on.. When doing these things it fixed the problem temporarily and I'd recieve all texts in a bulk, it would work for ten minutes then it goes back to not receiving again. Please can someone help me, I've tried everything and just to mention the phone is 4 months old, never been dropped or no water damage. It needs to be fixed I do not pay monthly for this to fail on me