Finally received description of fix to problem with headlights that keep blowing.
Hyundai suggested to my dealer:
"You need to make sure that the globes fitted are genuine Hyundai, part number 18647 55007L. These are rated at 960 hours.
In regards to the headlight earths, you will need to check the resistance of each headlight earth circuit, making sure it is not excessively high.
What is the alternator charging output?
Check the wiring for the regulator back to the BCM, ensuring you have no poor connections at the plugs or any high resistance. This can cause the alternator to overcharge intermittently."
So far so good.
Apparently genuine Hyundai bulbs, made by Philips have 960 hour rating, rather than 480 hours of brighter bulbs.
I am happy to replace brighter bulbs twice as often, but want them to last 480 hours not 48 hours!