my vehicle has been making a loud wining or moaning sound

I am sick and tired of all the money I am putting into this vehicle to get this issue fixed. I have it in again today for this issue and again they want to changed my routers/wheel bearings. The problem is, every year they change at least one and every year it does not fix the problem. I take it to a Ford dealership. The very first year I took the vehicle in for this problem I was told that both front routers had to be changed. I could only afford the one so he fixed the side that it sounded where the howling was coming from. Luckily it was the right side and the noise went away. The mechanic said the other one also needs fixing eventually. The sound started coming back so I took the vehicle into a Ford dealership and they fixed the router that was suggested by the previous mechanic. That did not get rid of the noise. I then took it to another Ford dealership. Same thing, they wanted to change the routers/wheelbearings. Again it did not fix the noise. Today they want to do the same thing and the noise is now so loud that when I go at highway speed or a little faster the noise is so loud you cannot hear the radio. Why is it that a mechanic, not Ford authorized could fix the problem but a Ford authorized dealership cannot? They are hosing me for a lot of money. Should these routers/wheel bearings be wearing out like this every year?