bad treatment by staff member

worse customer service at Maponya just now a lady sitting at booth 6 I went there to return a modem that my brother bought online it was delivered he was not at home he is a truck driver he comes home once a month now he is on leave he told me its not what he wanted the lady told me about 7 days policy which was never explained to me when delivery was made she continued to tell me that there's is nothing she can do with an attitude and there was change of words until I asked to to the manager because honestly we cant keep something that wont serve the purpose, the sales lady continued asking me why didn't I open the package clearly if I can sign for it I can open it which I found very strange because signing for a package that's not yours does not give you a right to open it the modem is still sealed my brother only open the packaging box please assist my number is ***