OK, checked it out. Get rid of the label you currently have for the report title. Insert a text box without it's label. Set this text box to:
="Customer Complaints for the Week " & [Start Date] & " thru " & [End Date]
Notice you entered those values as the parameter when the report opened.
="Customer Complaints for the Week " & [Start Date] & " thru " & [End Date]
Notice you entered those values as the parameter when the report opened.