Wow..this does not sound like a very professional shop..did they state the reason for the welding of the shaft..sounds like they took two and made one..the gears are part of the long shaft and would explain the graft but not the fact that the horn wire will no longer thread the hole...how far up the shaft is the weld? can a long bit (available to 18") be used to possibily clean the weld? I know it should not be your job to come behind their work. Second is the quality of the weld itself..do you trust this weld...is the weld a documented repair from them..ultimate responsibilty rest on you..documentation can make them responsible but at what cost to you, your family etc. These are question we must all face when making mods/repairs to vehicles. More than not the weld is secure and you have only the inconvience of not being able to use your stock horn button...I would not be happy paying for this service and have a unit rendered out-of-stock specs and application.
When you returned this unit..did you point out the horn wire problem? Else they may not really be aware of the need to have the hole unobstructed...