New phone doesn't work

After we collected our new phone on contract at Vodacom the phone were not in a working condition. We took the phone back and received it back after a while still not working. So we took it back again for the second time and received it again in the same condition. When we took it back for the third time they told us they will send it to Samsung. After two weeks we received the phone and they told us we must test it for a week or two. We used the phone now for almost a month and it is still not working properly. On the 26th of May we took it back and we are now still waiting for a response. We are struggling from the 7th of March with this problem.