Vive controllers need repair without warranty - HTC can't book them in for repair

[veridis.quo]

So I have two vive controllers that need to be repaired, one from the original set of a 2016 made in taiwan headset and another controller i have bought online through a re-seller. 
One of the original remotes got lost so we had to buy a replacement for it. We never had a real issue with the remotes but now one of them keeps flying away if put upside down and the other one has the trackpad stuck.

Both controllers don't have warranty but I didn't care about that, i just didn't want to buy two new ones (even thol' itmight be a better deal than to have them repaired for over 60 usd for just 3 month warranty)

>HTC vive support tells me they can't book it because i can't provide the serial number of the remotes.
>Both remotes look the same and have the same writing on the back of them.
>Even if i knew the S/N of them, if for example I wanted to send ONE OF THEM, i still WOULDN'T HAVE ANY WAY OF FINDING OT WHICH ONE IS serial A and the other.. serial B.

>This being said somehow it is my problem I didn't keep the original box for 2 years just so I can provide HTC support the serial numbers of their products

Please HTC vive,
Find a solution for this issue.