There is some silly advice and silly opinions being given on this subject.
Fill in the form, which you have done, or send a letter outlining your case. Simple as that.
If you come up against a brick wall threaten them with the small claims court, and put time limits on when you expect their replies.
You don’t need to do FOI Act requests or requests for risk assessments at this point, if you ever will need to.
Keep it simple, send them an invoice for repair, tell them you have video evidence, are willing to go to court to recover costs and the matter will find its way to the legal department.