How do I get rid of the old messages that keep coming in constantly after deleting them?

Ok, I have a brand new galaxy S7 Edge (week old). I was texting one day and within 5 mins. 20,000 old deleted text messages from my previous phone come in. Ok, fine. I deleted them all took me all day. Now they keep coming in daily after I delete them and it will not stop no matter how many times I delete it. Same messages. How do I get rid of them and make them stop coming in for good.

Hi, what network provider are you with? are you using the stock messaging app that came with the phone? there could be some sort of sync setting enabled, which is causing the messages to filter through.