Interesting that a Suzuki dealer can not work out the mode switch. By the way the default mode is "A" not "C" so every time you start it it will be in a "A" mode no mater what it was when you stopped it. You vere "testing" it at the 600cc power level. May I suggest another dealer altogether to get you bike from because if that reflects their knowledge of the product they sell, imagine the service you get from them after.
"It is not a shame to not know, the shame is to not know and not to ask"