a300 unlock without cable?

Hi all,

I'm reading contrasting info about unlocking the a300: from here and other forums it appears that newer ones can be unlocked only with a cable, but there are lots of sites offering to provide a code given the IMEI. I tried all the codes floating around (*2767*..., *#9998*...) and none work: I still get "enter network unlock code" whith a SIM in. The weird thing is that the phone worked with the same SIM until yesterday... I have tried many Orange UK SIMs, always the same message (no SIMs of other networks yet). Orange and Samsung said there's nothing to do, but we all know that's bullshit. Any ideas? I don't have a cable and don't intend to buy one, shall I spend £3 for an unlock code or are they just going to give me one of the codes I've already tried?
Thanks in advance.