Faulty modem purchased

A modem was purchased from Sibusiso Zimu on 28/05/2015 and we discovered the modem was faulty/broken when getting home. It was returned back to the shop (Cell C - Highveld Mall) on 29 May hoping to get assistance? and what a bad attitude from Sibusiso who was not willing to help at all?. The device came out box broken and we expected kind assistance from him. We were told we damaged it and should purchase another device if we still interested. He was even refusing to speak to me over the phone when I called, imagine. Till now the problem has not been solved and we are stuck with a damaged device. What hurts the most is the bad service recieved, bad attitude and no willingness to help. I am still asking myself if Cell C traets their customers like this when having problems. My brother, sister, and I are on Cell and we are considering switching to a different network provider e.g. Vodacom or MTN.