Vodafone mobile broadband with free laptop - what are my rights cos it doesn't work?

[Monty]

I bought one of those free laptop with a vodafone dongle deals in sept 2009. I've been back and to to vodafone customer services and pc world (where I bought it from) ever since. I have never been able to get the internet to connect. I've already had one replacement laptop as the motherboard was faulty, then vodafone switched my contract off for 3 months and insisted I had asked them to but I didn't. They credited my account but that made it difficult to establish whether my broadband would work too. Now, after yet another trip to PC world where they assured me there was no reason why it wouldn't work (they checked the laptop, signal etc), I'm still without the internet. What are my rights here? Do I have to continue to pay the remainder of a 2 year contract even though I will probably never be able to access the internet? Thank you