Bad quality of watch

Good day

I purchased a Tempo watch on the 24th December 2018 for a christmas present, a month later the colour is going different like it has gone copper. It feels like it wasnt proper silver

I went to the Amercian Swiss in Fourways mall in JHB where i purchased the product on the 27 January, the ladies at the store literally told me that my girlfriend has abused the watch and therefore thats why it has changed colour. How in a month can the watch be abused, very disappointed in the treatment received.