I have a sim only contract at present but need to upgrade or change my phone to a bigger screen,
am i able to do this on sim only please, thanks
SIM only is exactly as it sounds, the SIM with its associated service, no handset cost due to none being involved.
In the case of wanting to stay SIM only and not upgrade to a contract which includes the monthly cost of paying for a handset, then buy yourself a phone from VM from their PAYG stock: http://store.virginmedia.com/virgin-media-mobile/pay-as-you-go-phones.html - just toss away the PAYG some which comes with said PAYG phone you buy and pop your own SIM into it.
Or, just buy an unlocked phone from somewhere else (definately cheaper!!!) and use that.
I personally would not buy a phone from VM, as they are overpriced to be honest, (and their phones are locked to VM, and 4G is not enabled, should you choose to move to a supplier who offers it)
Look for a good second hand one that you like, and pay far less than for new...just make sure it is unlocked to any network..