iPhone 4S locked to Vodafone .

I have for sale an iPhone 4S locked to Vodafone, I bought this a few weeks ago hoping to be able to get it to work on my current network (T-Mobile) and bought a genie sim to enable me to do this. However, I cant get the interenet to work on it so am sticking with my current handset and am now selling the iPhone. The phone is in good condition its got a few scuff marks on the back but nothing serious and is in full working order. I will not accept payment via paypal, its cash on collection only. Collection is from Heckmondwike West Yorkshire. I will also include the genie sim card if its required.