VE smart alternator doesn’t work the same was as old dumb alternators so the auto elec needs to be aware of that when checking these vehicles. These smart alternators are controlled by the BCM which measures battery state of charge level among other things and it decides how much charge the alternator should throw into the battery. IIRC there was some service bulletin which updated the BCM firmware(?) to adjust the charge algorithm but I’m not across the details.
A dealer service tech can check that the latest software is loaded to all modules, for a fee.
I’d assume the auto elec did a battery load test and checked the (smart) alternator charges the battery correctly. If so and all was well, then you’d have a parasitic drain issue which is sucking the life from your battery. Parasitic drain issue can be as simple as a door switch not working so the vehicle system doesn’t go to sleep or it can be complex and time consuming to find what device is causing it.
In any case, IIRC, VE came standard with a basic alarm though some dealers fitted an upgrade… the alarm upgrade was possibly done with poor wiring standards, etc… It may be this dealer option that is now faulty but a good auto elect would have found the exact cause and resolved it (or clearly identified and isolated the faulty circuit).
I’d have another chat with the auto elec and clarify exactly what the problem is and what needs to be done to correct it, whether the alarm upgrade module (or whatever) acan be removed and the system reverted to the standard factory alarm, etc.
If he can’t oblige with some clear details, you may need to go another auto elec or a dealer (unless you’re good at automotive electrical issues and fault finding, then DIY)…
