What could the problem be?

Ok, so. I've owned an enV3 for about a year and a half now and had absolutely zero problems until this month (Surprising seeing as these things tend to break quite easily). Having heard that these phones tend to break I took the phone to the verizon store to see what could be done. The phone would; say a message had failed when it had actually sent, send triples of the same message, wait until I had at least 3 other messages to receive before I received any, and had issues calling people. So when I went to the store they removed the messaging and calling capabilities and restored the phone and gave it back. That worked fine for about 5 days. Then all of those problems started to happen again. Figuring it was the phone, I moved my number onto my backup phone (a motorola razr, remember those?). The same issues (mainly the saying a message had failed when it had really been sent) popped up in a matter of minutes. I again figured it was the phone and switched to my friends old enV touch... the problems still followed. Now I have no idea what the problem could be. It can't be the phones, I've gone through three of them and the older ones had worked flawlessly before. Could the problem be within my number? In my house my brother and mom both use their phones and have no issues whatsoever. Does anybody have a clue as to what is going on? Thanks.