Damaged hire van - what are my rights?

jimbow25

I hired a self-drive van this week in which I moved house. As I am inexperienced I took the precaution of paying extra to get the excess lowered from £500 to £100.

I then had an encounter with a bollard which damaged 2 panels of the van. Upon returning today I was honest about what had happened and was told I need to pay the £100 excess and it mentioned informally that it looked like 'about a grand's worth of damage' (the 2 panels are quite damaged and may need replacing I'd guess). I signed off the paperwork, paid the balance and left.

I then had a voicemail about 30 minutes later stating that the terms and conditions in fact state that there is 'no insurance' for negligent damage such as crashing into a bollard (or a tree etc) and therefore I am liable in full but I will be called again tomorrow with an exact quote. Indeed it does say this in the small print (albeit tucked away on the back of the agreement so I wasn't actually aware of this FWIW).

Am I liable for this in full?
Does the fact that I signed off agreeing to pay £100 only help me at all? As far as I was concerned - and seemingly as far as they were concerned too - I had paid that to settle the issue.
Is there anything I can do?
I'm sure as far as they are concerned they will deliver a quote and want to charge my credit card right away. What are my rights?
I obviously felt pretty foolish over what had happened and did not gladly pay £100 but the prospect of that increasing say 10x is quite chilling!