@madz03: If the issue is only affecting certain contacts, then please open the Messages app > Tap the 3 dots in the top right > Settings > Block Numbers and Messages > Block numbers, and remove any relevant contact numbers from here. Tap the Back button to return to the Messages settings screen > More Settings > Text Messages, and make sure that there is a number populated in the Message Centre field > Back > Delete Old Messages On. If the messages contain pictures or emojis then try enabling Mobile Data by swiping from the top of the screen to the bottom > Mobile Data, to see if this helps.I'd also recommend reaching out to your network to ensure that there are no problems with the service in your area. Let me know how you get on.
If you moved SIM card between phones and you are still not getting messages, it is likely that the issue is with the SIM card and the network provider. I recommend getting in touch with your email provider to request a replacement SIM card and to ensure that your provider is not experiencing any issue in your area.
