Worst f,ing service ever

After complaining for 2 weeks about 1 of the samsung j8,s that I bought and paid cash for, vodacom still don't want to give us a new phone, that was a out of box failure phone even the store where we bought it told us, it went in for repairs and when it came back it still wasn't working and now the store sent it back for repairs, which means vodacom couldn't repair it in the 1st place, now dealing with a person named colleen who is a vd at vodacom and yet they still don't want to do anything about the phone, this is the worst service ever, I'm really getting sick of this they where quick to take my r12000.00 for the 2 phones, this is not on, vodacom disobey the consumer act completely, do I need to get in care blanched for this