2000 Ford Ranger water pump

Had water pump replaced. When leaving shop I noticed a loud squeking noise, returned truck to shop, mechanic said alternater barring was going bad. Took truclk to Auto Zone and had them check the new Alternater that was in the truck, they said the noise was coming from my idler pulley and fan shaft and/or clutch, took truck back to mechanic, he replaced idle pulley and fan clutch but the noise is still occuring. Mechanic said it was alternater baring going bad, took truck back to auto zone where I purchased alternater, they tested it and said alternater is fine. I read in Haynes book if the water pump shaft barrings fail there may be a howling sound at front of engine. Haynes "quotes" don't mistake dry belt slippage for water barring failure.
What should I tell Pep Boys mechanic when I take it back in?