I am guessing that you have this relationship:
Customers::__pkCustomerID = Shop Data::_fkCustomerID
Your field names may differ from mine but what you describe should use an ID that uniquely identifies each customer and Shop Data would have a record for each time a customer visits your shop.
With such a set up, you can set up a report layout based on Shop Data, perform a find to find all records for a given date or range of dates and then (most likely) sort the records to group them by date or by customer. Sub Summary layout parts can be added to serve as "sub headings" if your report needs such.
That's just a very general outline of what should work for you. Feel free to use Post a new Answer to respond with follow up questions specific to your reporting needs.