Samsung SCG C300 need to unlock

Okay - I know its an old phone, but I live in an area with little or no reception for mobiles, so simple is great for me for emergency use.

I haven't used the phone much and recently found out that the Tesco/O2 network seems to get a reasonable signal about 100ft from my front door, which believe me is good. In fact having borrowed a real cheapie from a friend who bought a mobile in Tesco for 15 euros (also a samsung) I can actually get a signal in my kitchen - Happy days - or so I thought.

Anyway, got a sim card from Tesco and popped it into my phone, not having used it for about two years and got locked out of the phone because it was the "wrong sim"

I then discovered that my own Samsung was locked into Vodafone so I phoned them and found them distinctly unhelpful. Apparently they have taken the number (fair enough, apparently by law they can/have? to do this). I told them that all I wanted to do was unlock the phone - their advice was to but another sim card (5 euros) build up somewhere in the region of 120 euros worth of credit - oh really!!!!!!!!!!!!!!!

I have now got the hump - my phone is like new and I am happy with it. So I then surfed the internet and found that I can unlock the phone, however, whatever way I seem to do it, it doesn't want to unlock, maybe its because the number on the sim isn't valid - not too sure. Some say take out the sim altogether and others don't and some want 30 dollars or more to unlock a phone.

Another way is to get someone with a current Vodafone phone to get all the details to do it for me using the number on the back of my battery. Tried everyone I know and all are on O2.

For me this is now a matter of principal - can anyone help????????????

I have bought a phone fom Tesco, but would really like my oldie but goodie up and running

Thanks