Broken watch strap/Bad service

I bought a watch using my credit account on 17 December at Truworths Adderley Street Cape Town. On 18 December when i wear the watch the strap broke. I returned the watch on 31 Dec and they said that they will take it to their quality assurance department. After 3 weeks i went to the store and they told me that the watch was rejected by quality assurance. I asked the lady who was assisting to call the manager so i can speak with her, the manager told me that the watch is rejected and there is nothing they can do. I reported to their Facebook page and the feedback was " it was established the fault is not manufacturing". So now im paying a watch that i did not use. Truworths does not care about their account holders.