I noticed on my way back into town yesterday that an Exxon I have shopped for years is now Marathon. When I did a shop last week at an Exxon he told me they were rebranding to Valero. I wondered what happened to all the Exxon's I used to do and I think I know now.
Marathon owns Speedway, nothing to do with Exxon. The gas station owner just decided to switch brand and supplier. I've been doing a location for years that went from Mobil to Gulf to Shell and now Mobil again.
Marathon is popping up a lot in my area, Valero, too. Many stations were generic gas before. Exxons that had co-branded with Circle K are now only Circle K. The whole petroleum industry may be obsolete eventually!
You probably have one large franchisee there that owns a bunch of stations and the franchisee is dumping E/M for another brand. Not a big deal, except for you who no longer gets to audit them, which stinks.
Seriously, nobody cares that you're offended.
I had one location several years ago that I did 4 different shops / types of shops over the course of 1 month...#1 was the original brand, #2 was the debrand, #3 was the new brand, #4 was the check of the new brand's branding elements. I never had rotation issues because they were different types of shops.