Non existent help with faulty fit bit after 1 hour

I went into the Somerset Mall branch of incredible connection to by a Fitbit Charge 4 at 11.20 am. I then went home and only once I went to open the item realized it was not sealed and had been opened in the passed. I however decided to anyway continue and attempted to turn the item on. When I tried to turn it on it only vibrated but would not turn on. I immediately went back to the store to exchange the devise. On the return to the store I found the staff to be completely unhelpful and unwilling to exchange the item saying it was the companies policy not to exchange the item and that I should contact their supplier directly. I found this completely unacceptable as the item cost R3000 and I had only purchased it one and a half hours earlier I then requested to see the manager. The manager then came out of his office with a printed 6 page warranty from their supplier with a whole warranty procedure and completely unwilling to resolve the issue. If this is their policy on returns why was this never told to me before I purchased the item and why did they sell me an item that had clearly been opened in the passed. I then forced them to take the item and to tell their supplier I want a complete refund as I will never purchase anything from Incredible Connection again.