Hi,
This is directly related to your Joomla and has nothing to do with our template (Asymmetric). Unfortunately we don't provide free support or step-by-step instructions if the issue is not related to our extensions.
I recommend you not to use any 3rd party SEF Component (sh404sef, ArtioSEF etc..) Because joomla SEF is good enough to take care the SEF URLs. Also, make sure you don't have more than 1 menu item for Shopping Cart. (don't forget to check the "trashed". Because if you create menu item and send it to trash, it will still effect the SEF. Make sure you have only 1 menu item for:
- VM Frontpage
- VM Shopping Cart Page
then the SEF URL will be generated based on this menu item. Auto generated SEF URL's are generated based on joomla menu items, don't forget that.
regards.
Support