Problems with Nexus

In August last year I bought a Google/Axus Nexus tablet. It was delivered, and although it worked fine with Wi-Fi, but I have never been able to use it to connect to the internet via the cellphone connection. I contacted them immediately. After an exchange of a number of e-mails suggesting parameter changes which I tried I still could not get the cellphone working. <br> <br> I took it to Johannesburg where it was found that indeed the Nexus would not make the internet connection.<br> <br> In March the Nexus was sent to Johannesburg for repair. On returned I tried to use it. The fist time it ran for a while, again connecting via Wi-Fi. The second time I switched it on it wanted to upgrade Android, and started to do so automatically. After a while it indicated that an error had occurred with the process. The next time I switched it on it went immediately into an endless loop. I could not stop it, and it went on until the battery ran flat.<br> <br> The result now is that I have had the Nexus for 11 months, and have had no effective use of it, and in fact now it is unuseable.<br> <br> I have put this to First Shop, and asked for a refund on return of the Nexus, but they are saying I should return it for repair.