Dell Inspiron 14 7437 wifi connection really horrible!!

The Dell Inspiron 14 7437 wifi connection is really horrible. I just bought this laptop in December, 2013 and I found it can't connect to the wifi! Sometimes I can connect it to the wifi, but it's very week and not stable. I used another laptop in the same location and the signal is much stronger and it won't be disconnected. I called the technical support, but they said they can't find my service tag since I bought it in BestBuy and I need to contact BestBuy first. I'm not satisfied with the answer and I really want to return the laptop... Is there anyone who bought this model of laptop have the same bad experience? How did you solve it?  Thanks!