my phone is still the same

I bought a Sony experia z3 in norwood on the 15th or 16th December 2015 in cash 10 000.00 and couple of cents. I updated my insurance as i still wanted my phone to have an insurance. My phone cracked in 09march I sent it for repair it took 1 month to come back. When it came back I had to pay a fee of R750.00 which is understandable when I get home it gave me a problem of not having signal . I took it back and they booked it for repair I asked if it won't give me any other problems in future the store manager of sandton Freddy said no. I started using my phone yesterday still it doesn't have a network. Now its 3 full months without a phone that I even paid cash. Vodacom they can't even swap it they'll keep on doing repair instead of swapping with another on.I'm not happy with there service