Mobile Users: Redirect to a different page when they click on a link

I have an affiliate website and am having problems sending mobile users to the right page on the merchants website.

When a mobile user clicks on the standard affiliate link it doesnt work. I need to provide mobile users with a different URL (.mobi).

Currently I have my mobile setup using WP touch pro (a mobile plugin) but my theme also has responsive design.

I currently have a gateway page, in wordpress, that appears after a user clicks on the 'buy' link where they choose their country location (to send them to the right external webpage), before going to the merchants site.

Is it possible to either send the mobile user to a different page when they click on the 'buy' link (e.g. Gateway page 2)?

or

Use the same gateway page to send users to a different external URL depending if they are a mobile user or not?

I really appreciate your help!