Why are more than 50% of my texts anonymous or text messages unreceived

[AC Question]

More than 1/2 of my text messages from friends are marked unreceived. Even though there is a prompt to download, they won't no matter how many attempts. I also get several dozen texts marked anonymous each day. The other day 128 messages down load from days past. I also receive the same text every 20min for 24 hours at a time. This phone had been a HUGE disappointment. PLEASE HELP if you can!