I can't get the bottom bolt out from the rear shock absorber on my 2000 Cit?

I am trying to replace the rear shock absorbers on a citroen berlingo. I have got the top nut and bolt free so now the absorber is fixed to the car by the lower bolt only. I have got the nut off but I can't get the bolt pushed through. I have tried using a spanner, thinking it may be threaded through the hole but this does not seem to be the case and I have tried hitting it with a hammer ( as with the upper bolt, which worked) but I am afraid to use too much force as the sound tells me it really doesn't want to move like that. Can anyone help?