Welcome to the forum. First rule to learn, we cannot divulge (and should never ask) the name of specific customers for our MSC companies.
You are allowed to ask "who shops grocery stores", or gas stations, or banks. But you may not name the customer by name.
You can alter your posting to a more general question.
If Hy-Vee is shopped, you'll find the company if you sign up with all the companies listed below under Official List Of Mystery Shopping Companies.