Clock setting with aftermarket stereo fitted

Warning! New owner dumb question...

Is there any way to adjust the Renault central clock display when you have removed the standard stereo unit and fitted an aftermarket headunit?. My car doesn't have the 2 upper buttons and was (i think) set using the original stereo. Having removed the battery to do a simple job i've now got a flashing clock display with no easily apparent way to reset it. I was hoping the stalk controls would have a way of doing this - anyone found a solution? I cant be the only person to have had this!!. I wouldn't care if it had disappeared completely but its flashing with the wrong numbers and will get right on my tit$...Any help would be greatly appreciated.