Badly repaired

Samsung has ADH Premium for in case your screen cracks or it gets water damage they fix it 2 times. My Samsung Galaxy S5 fell and the screen cracked , they took my phone and fixed it but I saw water still could get in the phone. And on the 26-01-2015 I called them to collect the phone to fix it for water damage and about a month after they phoned to tell me that they can fix the screen but I must pay R3 000 or more that they could fix the motherboard. But if they fixed the screen right on the first time the motherboard would not have been damaged. Now they want to Collete the phone they gave me to use while they fix my phone and give me a broken phone back but it is the 2nd break what means it is still under warranty