Unhappy with NWJ's incompetence

We bought a Daniel Klein watch at NWJ Menlyn on 29/11/2017. There were many problems with the watch: 1. The strap was too long, which they said they could make smaller but it turned out that they could not. 2. Then the diamantè on the watch dial fell off, they fixed it. 3. Then the battery stopped working, they fixed it 4. As we collected it, the shop assistant noticed that the diamantè was off again. The watch was sent in again on the 18/02/2018, to be repaired. NWJ was cunning to let the watch stay in their possession until the 3 month guarantee slipped. They came up with excuses that the public holidays delayed them. It is now 10/04/2018, I got a call from NWJ to inform me that I have to pay R135 to have the diamantè fixed and they said that the guarantee purtains only to the watch mechanisms and not the detail on the watch. So, this watch was never worn since we bought it, but now suddenly we have to pay in, to fix it.