Wow-- Thanks for all the support. Very funny, elcarev68. That's my mindset exactly!
I would be hard pressed to give up this msc entirely, as they are very responsive, professional, kind, and provide a large portion of my work.
Shop-et-al, I understand where you're coming from. The companies, at various levels, do tend to try to exclude negative shops whenever possible, but the shop was average. They missed a few points, but nothing that would cause a lawsuit for sure.
I have a feeling it would not be good to call them and mention anything about me having done a shop there. You're never supposed to contact the client regarding a shop. But, perhaps I could do it like some of you described and act like a regular customer. BUT apparently the msc has already done the calling *twice* to try to make a positive identification, even using the physical description I gave.
I'm inspired by risinghorizon's experience of providing more and more detail until they accept it. I offered to describe the employee better, but even if I could get them to agree, would they pay me after another shopper has gone out and done the shop? I do have a receipt, but the name is apparently such an important requirement that it overrides the proof that I was at the location....like the whole report is useless without knowing who I interacted with.
I appreciate everyone's tips for obtaining a name accurately. From now on, I will definitely use the one of repeating it back.