Hi,
HikaShop uses Bootstrap responsive design. If your template is not compatible with Bootstrap it won't work and you will see one single column for your listings.
At this moment you have to deactivate the "bootstrap design".
Bootstrap is the responsive framework chosen by Joomla, that's why we made an integration with this specific framework which is include in Joomla 3.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.