The Parts Counter

Hey fellow parts peeps I was hoping to get some advice on how to handle my current situation. I was recently promoted to manager of one of brands in a dual branded dealership. Previous manager who has been doing both store for years has been told to just focus on the other brand. Unfortunately He hasn't been willing to give up the other brand. Currently both brands are taking a hit because Current manager is being pulled into too many directions and doesn't have time for both. Just feel like I'm between a rock and hard place and not sure how to handle this. It's been 3 months and my brands numbers are continuing to dip and I'm starting to take the heat for it.