what type/size of engine is it? you'll need to be very careful if it's a 1.4 or 1.6 as the crank pulley has no key, so as soon as the bolt is undone, the cams and crank turn on their own. if it's a 1.8 or 2.0, you could try the old breaker bar on the floor trick. Simply stick a breaker bar and socket on the bottom pulley and flick the key. you'll need the breaker bar resting on the floor at about 4 o'clock position when looking directly at the pulley. if you have it the other way (8 o'clock), it'll smash into your subframe or whatever else is in the way. It's a risky move, but i've done it several times over the years and never broken anything.