boot lock fault?

the central locking on my 206 cc is not working, so I have been using key to unlock boot. Now however the key will not turn to unlock the boot, the button can be pressed in, and the key will turn to the lock position but not unlock, therefore the boot cannot be opened. I have removed rear seats but there is no access to boot this way. As the boot cover is retracted I cannot get the top boot cover for the roof to open. how can I get into the boot.