Last week I had to remove the audio unit in the OH's Sportka (to replace the heater control panel) I used a couple of small allen keys, did one pair of holes at a time. The keys were the kind with a small 'bullet' on the end to allow angled operation - these bullets clicked in nicely. Difficult to explain, sorry..... If you press the keys outwards, then use them to pull the unit, it works. Then the same for the other pair of holes and Robert's your mother's brother.
HTH