Continued bad service

Good day <br> <br> <br> A while back (in this month) I complained about Altech Autopage's bad service.Story from the beginning :On 21 November we upgraded on our contract at Altech Autopage ***.on the 27th the phone started switching off, lady said its software update even though it was an OBF phone. on 4 Dec the phone went off completely so we took it back and they sent it in for repairs. <br> But NOW: we received a new phone on 24 December from them after the guy from National consumers act phoned them. The contract amount is R380 (which is R110 for airtime and R270 for the phone) so we upgraded on 21 November 2015 and gave the phone in on 4 December 2015 which gave us 2 weeks we used it. They can see on the system when last was the phone used and sent in yet they want to bill us R349 for something we didn't use, I told them fine I would pay for the airtime but im not paying for the phone , the lady at altech customer service was rude to me yesterday even started shouting at me when I said but why must I pay that amount, she kept on saying its for the sim but when I told her the sim(airtime) is only R110 then she said yes the rest is for the phone.So please do tell me if im wrong?