I found that the dead pixel line was usually minimized or eliminated by using the lowest native ISO on the camera. It is a function of gain and that particular pixel. You may try reloading the current firmware which may kind of knock the sensor map around. Leica told me on the phone to do that once when I got the camera back from sensor remapping and three days later the line came up somewhere different.
There are a few programs out there for removing the line but I am a Linux user and they are all open source. I don't know if any have been ported to Windoze or Mac. You could try Darktable at first. It has a rudimentary dead pixel removal tool in there, or did when I was involved in the project. UFRaw can map hot pixels out and normalize them based upon the surrounding pixels. You can dial in strength of the reduction that way. I haven't had a digital Leica since 2012 so I have forgotten the specifics of how I dealt with the problem in the short term.