Wifi woes

I walked in a store on 9/23 and was told to try the TMobile for free. Instead, I returned it 4 days later as it could not compare with Ziply and Tmobile is charging me $30 a month even though I returned it. They also messed up my bill, cannot help me on the customer service line since I don't know my pin and they don't accept Social Security numbers as back-up anymore. I was told I had to go back in a store. 

Terrible customer service.