Phone under warranty not repaired

I have a LG40 under guarantee and it stopped charging 3 months into the contract. I contacted Virgin and the phone was send back to them for repairs. I received and sms to say that there is a quote of R240 for the phone and a service agent will contact me. I waited for a week and then i had to phone THEM. I asked what is the problem as the phone is still under guarantee and was told it was the battery that was faulty and it carried a 6 month guarantee and it will be replaced without any cost to me. I was a happy customer then. BUT low and behold the phone was send back to me. I was happy to receive it back and opened it at the courier company just to check that it is the correct phone. How big was my surprise and annoyance to discover that it was still faulty WITH THE SAME PROBLEM!! I called virgin again and ask to speak to a supervisor was told she would phone me back, no phone call yet. Phone went back and i got sms to say there is a quote of R240, again! I think its utterly bad service and the person who worked on the phone is totally ***********. I have to pay the rental still. Very bad service