there is a solution; there always is.
now, i dont like or use hte iphone for a lot of reasons, but i know there is software out there that will allow you to back up your text messages.
I know for sure, ive seen the database file(s) that the iphone uses for storing its texts (this was on a jailbroken phone...)
so, the best thing is to check this out:
Let me google that for you