That's great service.  I'm glad they're able to solve your problem.

MAKE them do the audio update if it hasn't been done.  Mine is 5-1/2 years old (six in November when I bought it), and it did the same thing and since the audio update and new battery it has never been replaced!  Knock wood!  I checked the battery voltage just the other day after it had been parked for 3 days with no charger on it and it read 12.4V on my meter.  The only time I put a battery tender on it is when I know it will be parked for at least 3 weeks, which is maybe once every 2 years if we leave the country.  Starts first time every time no problem.  It's your audio unit that is the problem.  Accept that and get them to fix it!

First thing you should change is the brake and shifter pivot arrangement.  Posts on the forum with details of how to eliminate a future problem easily.  Lots of help in your part of the world, not so much in the US.

Just finished the RocketSteve pivot solution a little while ago.  A little time consuming to set up the original parts in the cross slide vise on the drill press to make sure I got them drilled in the center (yes I had a spare and drilled the first one as a test and it was OK), but that was accomplished and both sides got converted.  A 5/16" (7.9248 mm)US drill bit is perfect for an 8 mm socket head to pass through without more than a couple of thousandth's inch (.05 mm) per side clearance.  I bought 40mm black oxide socket head 12.9 bolts so they had a short unthreaded section under the head (mainly because that's what the store had) and cut them to fit and used copper anti seize on the threads, fresh silicone lube on the pivot (they were still clean and lubed with silicone from the last time I serviced them), and stainless lockwashers under the heads.  Done and done.  No more regular service.  They had gone through some particularly nasty weather since the last time I serviced them and there was no sign of any corrosion inside the parts or on the pivot bolt.  The silicone lube did it's job and kept water from causing any corrosion issues.  If I need to service them again I may go to stainless or softer socket head bolts but I'll use the silicone on the pivots again.
Thanks to all for their efforts to find and document a variety of solutions for this problem.  I think I chose the simplest one for me to accomplish.
Glenn