Sold me broken modem!!!!!!

After wasting much of my time in store, I was eventually sold a modem that didn't work at all. I was sold the modem without a power supply, which I had to acquire. No cables were incuded. I should have smelled a rat but I assumed they would have tested it. On returning the item I was kept waiting for half an hour while they 'tested' the modem. Try doing that before you sell it. Time wasters and bad service.