If you want to be able to filter by both filters you should apply two filters to the aggregate,
having two local variables (one for the name searched and other for the choosen rating),
for example: local variable text: "NameSearched" ; local variable integer "RatingFilter" and supposing you give the default value for the rating filter -1, meaning whenever you don't pick a rating to filter the value of the variable is -1.
On the aggregate where you query the companies apply these filters:
1 - NameSearched = "" or Company.Name like "%NameSearched%"
2 - RatingFilter = -1 or Company.Rating = RatingFilter
This way, it will filter only by name, or only by rating or by both.