5 Weeks and still telling me there is nothing wron

Went to vodacom 5 weeks ago, telling them that the phone is malfunctioning. The device has been sent back 4 times now and yet still the phone hasnt been fixed. Now they are sending the phone back once again. No one can help me with regards of fixing the phone because your technicians are useless. I demand a new phone as I have been patient with vodacom in fixing my phone. I have been paying for the phone, loss of data and yet vodacom still refuses to fix my phone. I demand a new phone or my contract being cancelled with immidiate effect so that I can happily support another service provider that is not useless.