Forced to pay for something not explained to me. When i want a refund, nothing came forth. They still have my watch since October 2017

In June 2017 i took my Guess watch to their store for straps and battery replacement. In 3 October 2017 i went to fetch it and paid R1060.00. On the 6th October 2017the watch had stopped working. I went back on the 19 October 2017 to complain. I was told to pay another +-600 for service. I refused and told the sort it out because i could buy a new watch with R1600. Till to date they still have my watch. No call, no sms or anything from them.