If you have not seen any shops this month (!), check your E-mails. There may be one that says something like "other shoppers have performed the same shop and have found numerous discrepancies (or something in that vein).
You may have been removed from the program for being either too easy or the opposite and shall not be allowed back on until you call in, talk to a supervisor and understand why you were removed. The supervisor can explain it to you and allow you to once again, be in the company's good graces.
In any event, call on Monday and explain you have not seen any shops for that program. They can either assure you that nothing is wrong or, you have fallen outside of their algorithm and should talk to a supervisor.
Post removed as it violates the Forum guideline which states, "Do not reveal the clients of mystery shopping companies".