Lenovo z510 wi-fi problem.

Yesterday I bought a brand new Lenovo z510 laptop. Although I invested a large amount of money and everything seemed perfect, a noticed a very bad problem, that I don't know how to fix. When I try to connect to my wi-fi network, it connects, but after a while the connection turns into "Limited Connectivity". My Wireless card is N 7260. I searched the internet and read that other people with the same model had the same issue. I tried a newer version of the drivers, I tried re-installing the OS (I am using Win 7 on the laptop), I brought the laptop to the place where I bought it, and there it connected to 2 wi-fi networks without any problems and it worked a while without difficulties. They told me I can't replace the laptop, since there is no problem. However, back home everything went downhill. As much as I would like to think this is a problem, coming from my router, the fact that my other laptop connects flawlessly, prevents me from doing so. I am soon moving to the UK and I thought I will have a perfect new laptop. I guess I was wrong. I hope Lenovo releases new drivers soon that will fix the problem..If not, I don't know what to do with the laptop. Can you help me? I would really appreciate. Thank you.