What is the unlocking code for a Rover 620 radio?

I have just brought a Rover 620 and the radio is locked please help me with an unlocking code, some websites say it's from 拢25 upwards which I can't afford. Please help|||In order to attempt to calculate your code ,the radio will have to be extracted from the dashboard ...Then please quote your radio MAKE+MODEL plus ALL the NUMBERS+LETTERS on ANY LABELS , BARCODES or STAMPED IN THE METAL CASING