@Warnawoo: 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. If the issue persists, try your SIM card in another compatible phone, to see if the problem lies with the phone, or your network.
