I have had two different people on different networks tell me that they have sent me text messages that I've not received. I sometimes get their texts but not always. I've checked there are no numbers blocked on my phone, I've verified that their phones show the message as having been sent. I have cleared out loads of old messages in case there's a space issue. This is a big issue and has caused a lot of problems for me and I'm concerned who else is sending me messages that I'm not getting. Can anyone help?