Bad service on warranty

Well to start of I got a sony xperia m2 aqua and from the start it was a bad phone and option the speaker broke and also did the screen crack for no reason while I was typing on it , so I went to Vodacom in the waterfront in Bloemfontein and they told me there is nothing they can do about my problem but if you skip or forget to pay your Vodacom bill they don't hesitate to phone you and tell you to pay it now I would like you to contact me and tell me why I should pay it for bad to none service from you guys please ? because I really feel it is pathetic service and I am not happy at all and i am very close to leaving Vodacom and go to mtn or cell c where they at least listen to people with a problem . so please do give me a call and feedback thank you .