iPhone 4 searching/no service (new replacement phone)

After a few weeks and 12 arguments later I finally have my iPhone 4 back.

Let me run through quickly what happened today

-received iPhone

-no service/ searching... problem

-updated to newest iOS

-problems solved for about 5minutes

-no service/searching... problem

-plugged into iTunes

-restored iphone

-asked to update carrier settings (thought this was solve it)

-maybe not..

- present ; no service and searching.. problem

I have tried everything I have seen online

Erase network settings etc

Remove SIM card and set time manually with airplane mode on put in SIM card

Basically I've tried different variations of everything I've researched and nothings worked.

Should I contact my carrier or who???