I bought a pair of Audeo V90’s off eBay and when I put the serials into Target to check warranty information, one comes back as not on file, to call customer service. Obviously, I am not going to call customer service, but is that a thing? Not having a serial number on file? The aid seems to work alright. I did an initial fitting that seems to have the problems I have always had with HAs, a lot of noises that annoy me, but not a lot of improvement of my actual hearing. I am going to try some other, different settings to see if they help. I have come to realize that I will have to make a pretty major accommodation if I am going to be wearing aids.