How do I remove the radio from my NissanMicra?

Hi, I've just bought a 2003 Nissan Micra and do not have the radio code. The dealer told me I had to look at the back of the radio but I can't get it out. Does anyone have any tips ,I have removed the two screws underneath the unit but it won't budge. The dealer wants £40 just to remove it and look for the serial and then a further £30 to tell me the code. If i was that flushed I could have bought myself a new model??
Please help if you can.