Changed number - text issues

[Maskerade]

We changed my husband's number through o2 customer services. They warned us that for 24 hours the old one could still work to contact him. More than 3 days later and someone we didn't give the new number to has been able to text him via his old number. How is this possible and how do we stop it? We've blocked that individual but there will be others

[MI5]

@Maskerade 

Is it an iPhone?

If so, the old number will need removing from iCloud.

Otherwise, have you rebooted the phone?

[Maskerade]

Hi, it is an iphone. Thank you, I'll try and work out how to do that

[MI5 · Accepted solution]

@Maskerade 

Settings >Messages >Send and receive and untick the old number.

[MI5]

Also, Settings, tap the name at the top, names, phone number and email.