I'm looking at upgrading from my aged sim that is a little scratched etc and voda told me it'd cost an amount i cannot remember 25 or 35 maybe even the cost of a new prepay connection pack.
I'm just interested in preserving my phone number
depending on your phone you can make use of a pc connection to copy phone books
maybe even your phone has onboard memory so you can use that to store numbers not the sim card
Most phones have a phone memory for names and numbers as well as SIM, Copy the names and numbers onto the phone memory put in your new SIM and then copy them back to the SIM, If you don't have a phone that will do this borrow one, like the 6310i, Z600, there are lots of them the list goes on,
most dealers can transfer this for you, as far as i'm aware all "VODAFONE" owned retain outlets will do this free.
it's pretty easy.
if one refuses, don't buy a phone there and tell 20 people not to buy a phone there.