replace “chargers” with “lighter outlet” or “power point” and it makes more sense.
He’s using 12V accessories with the car off… it’s not clear how long the item is being used, but apparently it’s sufficient to drain the battery.
How do you end up getting the car started? Do you (or a tow truck driver) jump start it? If so, it sounds like a battery issue.
Bring it to the mechanic and ask them to check the alternator output… if they don’t have a machine that can test the output, then find a new mechanic.
Also, if you’ve drained your battery below the point where it can start the car 3X within one year, it sounds like you may need a new battery regardless of whether your charging system ends up being OK or not.