Rear End trouble advice needed

January 15th of this year I had bad vibrations coming from the drive line. A mechanic looked at it and told me that the pinion bearing was bad in the front drive axle. They didn't do axle work so I called around and found a shop that did.
The shop I took it too had no qualms about doing the work although their "truck" mechanic was not there that day. The trailer mechanics did the work.

Fast forward to January 27. The vibration is back and far worse. I go to another shop and they quickly determine that the inner bearing is bad. Of course now the outer bearing that was just replaced is shot again as well.
The inner bearing was broken and probably causing all of the problems. The shop it is at now says the other shop should have known to check both bearings.

What can I do. Do I just write off the money spent to do the earlier work?
Do I even bother to contact the first shop? When I called them yesterday they seemed to not even remember doing the work.(Yes, I have receipts).

 

I just talked to the first shop. They said there is no reason they can imagine for checking the inner bearing. They said they did everything they always do in the same situation. They will take no responsibility for anything.
EVERY other mechanic I've talked to said you always change both bearings, changing one is never a good idea.

 

American truck/Paul's trailer in Terre Haute IN.
Thanks for your advice.

 

You are correct, except that when I called them yesterday I spoke with the truck mechanic. He said he would not check the inner bearing. He says there is no reason to check it. That is where I have a problem with them. I've always thought that you check everything involved to find out what is causing the problem. Replacing a bad bearing without looking for why it went bad doesn't fix anything. It simply covers the problem temporarily.

The new shop (Affordable Truck Repair in Forest Park GA) sent the pumpkin out and had it set up by the guys that know what they are doing. They also said that they will guarantee it for 75,000 miles. Anything goes wrong they will fix it.
Now I just need to get a load and make some money.
Thanks again.