Sprint Verizon At&t empoyees

[molta]

hello all,
i'm having problems with my sprint mogul. every now and then whenever i call out i can't hear anything so i end up calling 2-3 times in a row with no result. so i after a soft reset i try the number again, then it works. now the people on the other end can hear me, cause they've told me that they've said "hello" multiple times and i wouldn't answer. also, typing is a drag as it takes a while for what is typed to be seen on screen. finally, every now and then GPS would not receive a signal. i have to soft reset to get it going. (sprintnav is GPS soft i use)
hard reset have not fixed the problems. a few days after a hard reset, the problems return. now i have taken it to the sprint store, and as with a breaking car, the phone worked fine and they sent me on my way.
i have not called sprint because i don't want to send it to them and they not find anything wrong and then i get charged.
what options do i have? ( i have the assurion insurance i pay monthly for.)
thnx