copy of genius bar exchange receipt

I exchanged faulty 3GS at the Genius Bar at Cabot Circus Bristol on March 5 2010.

As it was swapped, my network Vodafone UK will not unlock it as it does not have the correct IMEI number.

Can I please get a copy of the receipt showing the old IMEI and new IMEI exchanged so I can get Vodafone to unlock my phone

Thanks