I had the same problem... try changing the socket to one of the ceramic ones, and replace the bulb with a new one at the same time. I believe the contacts (both socket and bulb) become oxidized from the heat which creates more resistance (and more heat), which causes the bulbs to blow. (Oxidation on either one causes heat to oxidize the other, becoming a "vicious cycle")
These connectors are the perfect solution to fix the manufacturers shortcomings! Better than OEM in every way, heavier gauge wire than stock, and no chance of the socket melting (like the original ones did). In fact, the wiring was a full gauge heaver than OEM. A few suggestions for the repair:
1. Don't just replace the connector, replace the bulb at the same time - The reason is that the posts on the bulb are probably oxidized from the original heat that melted the socket to begin with. Oxidation causes resistance in the connection, and resistance causes heat. It won't melt the ceramic anymore, but will create additional heat that could melt attached wiring, oxidize the new connector contacts, or otherwise cause additional heat damage (headlight housing or otherwise)..
2. Leave the leads long on the connector - Because the wiring is probably larger gauge than what you are replacing, the longer/heavier lead will allow for more heat dissipation before reaching your OEM wiring. Shorten your OEM wires if you know you'll have too much/too long wiring when done.
3. Solder the splices - again, less resistance and heat, and a more reliable connection. Also use heat-shrink wiring sheathing to cover the splice (Helpful hint: Don't forget to put the sheathing on one of the leads BEFORE soldering!).
4. If you can get some, use some anti-oxidation paste on the terminals (just a little), again to prevent oxidation/resistance/heat. You can order on line or even buy at your local big-box home improvement retailer (either the orange or blue one, both carry at most stores)
5. If your original socket melted, there may be smoke residue causing cloudiness on the inside of the headlight housing. You can try using a diluted mixture of vinegar and water (50/50) to rinse out the inside of the housing. Make sure to rinse at least a second time with water and ensure that it is dry before reassembly (it may take a while to dry out).