Product Quantity Discount only on single options

Hi there,


Current problem is customers are able to mix and match options to reach the quantity for the discount.

I need to change it so that the discount is only applied if they have the qualifying amount of a single option.

for example the discount is at 12

i want them to only get this is they have

12xred

not if they have

3xblue
3xred
3xgreen
3xpurple


Ive had a search but not coming up with any results.


thanks

Thought id give this a bump,

Does anyone have any ideas or know of any extensions that would help?

an update incase anyone else has this problem

Found an extension that does exactly what im looking for,

http://www.opencart.com/index.php?route ... on_id=1888