You know, it's funny. I had just written up a response on how mine has lasted years and years so you must just be the victim of QA randomness or some other factor. But then I went to look for my receipt and when I couldn't find it, decided to see if I could google up some pictures of me using it at gigs. The first one I can find was in the fall of 2012, which would be about 21 months ago.
So while mine isn't that much older than yours, let me say this ... mine is still chugging along fine despite suffering many, many drops to the stage, drops to concrete, getting tossed around and generally beaten up. I've had one problem with that being the plastic barrel connector stripped out ages ago. For the longest time, it had absolutely no impact. Then a few gigs ago I started suffering what I initially thought were radio interference problems or dropouts, but recently realized it was that the cable was no longer holding itself firmly in.
Mind you, I pack my gear quickly. We stop playing, give some thank you's, spend a few moments with any audience members than I'm doing my best to get out of there as quickly as possible, so I literally just toss it into my guitar bag (with the cable connected). I was quite pleasantly surprised that I was able to get away with that all this time, and even played a few more gigs with it that way, just reminding myself to push it up firmly between sets. And frankly, I could probably shove a match stick in it, or a piece of folded paper, and keep on using it as-is.
Other than that one issue - which was the result of my dropping it (or more accurate, it leaping to its imminent doom)- it's quite honestly been a workhorse for me, I've been firmly evangelizing Line 6 wireless to anyone seeking wireless. A bandmate bought a wireless rig without consulting first - I won't name the brand, but he started having *serious* issues with it on gig 2.
As Boomer suggested, I would get yours checked out. Even if they charge a small diagnostics fee it's considerably cheaper than buying new ones.
Best of luck whichever you do !