Can't Receive Text Messages

[chippy901]

New to Android, new to A21s (two days!) after eight years of an iPhone. 

I've set it all up but it won't receive text messages.  Sending okay.  I went back to store and they changed the SIM which they said should cure it but it hasn't.  I'm going back to store tomorrow but wondered if any of you guys have a fix?  I saw something which said to clear data and cache, which I did, but no joy.

[chippy901]

Sadly I ended up changing phone number.  Apple say you can switch off iMessages but that didn't work.  They also say you can deregister online but guess what - they said a 6-digit code to you by text messages - which you can't get because you can't get text messages.  My new network provider did so much to help, I probably spent five hours in total in store with the tech guy but nothing worked.  Love my new Samsung phone, highly unlikely I will ever go back to an Apple product - this strikes me as anti-competitive behaviour.  So anyone out there wanting to switch from iPhone - deregister your iMessages before you move.