Hi,
www.hikashop.com/support/documentation/5...ashop-changelog.html
HikaShop 1.6.0 has now more than a year.
We made a lot of modification in HikaShop since August 2012 and the payment plugins have changed a lot.
That's why it will be difficult for us to provide you a update for the plugin, it won't be compatible with your current version.
The best will be to update HikaShop to a latest version and no, you won't loose your settings or your overrides.
Please make a full backup before (in order to be completely safe).
If you didn't modify any core file (use view/css overrides for your custom modification) you shouldn't have any trouble.
HikaShop has been made for being updated and keeping your settings and your design safe.
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.