How can I change filter function?

Default, filter module will work like this:

I have 20 products:
- 10 products -filter Brand A
+ 5 products - filter size 10
+ 5 products - filter size 20
- 10 products -filter Brand B
+ 5 products - filter size 10
+ 5 products - filter size 30

When I checked Brand A, will display only 10 products in brand A. But when I want filter product size 10 in brand A, it will show also 5 products size 10 brand B. Now I want it listed only product match with multi choice filter. Can anyone help me? Thanks

For anyone have same problem, I found a solution here. Thanks for author

http://www.opencart.com/index.php?route ... n_id=23603