Kia Silverlakes - a genuine rip-off

Vehicle sent to dealership for warranty repair (battery terminals). Remotes also 'dead' as a result of trying to activcate ignition. Asked KIA to replace key remote batteries. Without advising us, I was charged R90 per battery (Panasonic CR2032)...which retails for R 12 each at any store. Also charged R160 for labour to fit the batteries. How can they justify that? My liability as a result of a manufacturers fault. Will dissuade anyone from contracting through Kia Silverlakes. Totally disgusted. Is Kia the rip-off or the dealership...you decide!