Headlight Switch problems of the 2010 Cadillac SRX

I bought a used 2010 Cadillac Srx last December, drove it for about a week the noticed driver side headlight was out so went to autozone to check price of bulb $100 no way, so checked ebay and got 2 for $25. Headlight worked fine for about another month and driver side light went out again so I tried replacing it with the other bulb and it didn't work. Took vehicle by local Cadillac dealership and they told me it sounded like the ballast was bad which costs $225 just for part and $444 total w/labor. Told dealership to go ahead and replace it and headlight still didn't work. Dealership said condensation was in light causing it not to work and I needed a headlight replacement with total cost of $1700 which couldn't afford just for a headlight so I found one online for $275 and installed it myself and it worked fine for about another month now out again. Heavy rain for 3 days and I'm wondering if moisture is inside it because I removed the bumper again and switched bulbs from good side and put on bad side and bulb not working but bad side bulb is working on good side. I'm also going to replace the relay fuse to see if that work. Don't see why there is not a recall on this since there are so many complaints.