Can you get one of the nuts off? I've had to do this several times recently (the loo is right next to the bath and the condensation seems to do for all the metalwork...why can't they use proper brass???) and could always get off the one that was easier to turn (the RH one as you look at the loo, because I'm right-handed and it turns inwards) and then did a lot of wiggling to loosen the other one - actually the last time I did it the top part just came away from the back of the loo. But if you wiggled too hard you might break the porcelain
If that doesn't help you could try keeping on with the WD all evening so it has a chance to soak through.
Otherwise it'll be Luckymum's hacksaw.
There should be a better design!