Poor customer service and poor product knowledge from a whole store manager

I went to Clicks Protea Glen Mall and called an employee who was wearing a Clicks uniform not being aware that she's the manager, I asked her about the bottle warmers if they work with electricity or are they chargeable, with an attitude she answered "I don't know, I don't have kids" as if you need to have kids to have knowledge about your stock as a manager.. I was assisted by a very nice gentlemen who was packing stock by the name of Monwabisi (excellent customer service) he also said he was not sure and started reading the box and opened it to confirm my query.