Weird Electrical Problem (Extra Long)

[Zippy M3]

So a few days ago my central locking sytem wouln't work and I could only manually unlock each door. Then I looked at the fuses and noticed that #7 (Central Locking Sytem) fuse was burnt. So no problem I proceded to put another 7.5v fuse in there and immediately POP! Geez so I upped the ante and the 7.5v fuse, POP! 15v, POP! 20v, POP! and then finally the 25v works fine only now I don't know if that good for the car.

I finally realized that the system went out the day that I wired up my factory wing. I connected the two wires from the wing to the driver's side break light. So I unhooked those the their brake light wires and put a 5amp back in slot #7 and everything is fine.

So what do I do?
1) Connect the third brake light from the wing and put in the 25amp fuse.
2) Try to find another wire to hook the light up to and use the 5V.

Did I use the wrong ground wire in the first place? I just picked the one inside the drivers side back light.

Thanks a bunch.