Right brake light, headlight and blinker issue
 

Hi!

I'm having a Ford Mustang 2005 convertible.

My right headlight and my right brake light do not work and the right blinker blinking rapidly inside car when turning on without the light working. I've had it at the mechanic who checked the lightbulbs and the socket, which is not the problem. They are now saying they might need to replace the electric box (?) which would cost ~$400.

This is an issue I've read about in another forums that people have had, but have not yet found the solution for it. I do not have that much of knowledge about cars...

I am wondering if anyone here can tell me what the issue likely will be - and what the best way to fix it is! (Including how much it should roughly cost.

THANK YOU SO MUCH!

Best,
Carl