That has to be the most brazen insult to your intelligence that I've ever heard. Would you replace your TV because the plug was broken? F***ing arrogance of these guys, never ceases to appall me.

Anyway, just go in the back of the headlight assembly (owners manual should detail the bulb change procedure) and pull off the connector(s). On some models the turn signals and parking lights run off the same connector. To eliminate the harness, use a test light and verify that the turn signal feed from the plug is working.

Take a bit of fine steel wool, emery cloth, radio contact cleaner (Radio Shack), your wife's nail file board, or whatever, and clean the corrosion off the parts, including the bulb sockets, until they are bright and shiny. Put in new bulbs.

If necessary, re-solder any suspect connectors by heating the post/tube that the wire is in, pull out the wire, cut back the corroded end until you reach clean wire (might require a short splice, as the old piece may be corroded too far into the harness to allow re-attachment) and re-solder.
If none of this solves the problem, you'll need to look further up the harness for a loose connection, broken wire, etc.

And don't forget that there is a brown ground wire that needs to be, well, grounded to complete the circuit to each bulb. It's often easier to run a fresh wire from the socket to a good clean ground spot than trace the problem down at the other end.

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1986 560SL
2002 Toyota Camry
1993 Lexus