waterproof phone not waterproof

Gave my sony M2 aqua in to be repaired because the so called waterproof phone had water damage. They came back to me in about 14days and told me I have to pay R400 to repair it. We refused to pay for that because it was under warrentee. Now. About 21 days after that they say that the phone is with them but still broken I must come collect it. While my friends phone also got water damage and MTN replaced his Sony Z3<br> Why cant vodacom do that I pay way more that him per month as well. Vodacom has no good service to one of our family's phones. If i could I would not pay any longer for that phone and open an account with an other phone company. I'm sick of vodacom<br>