Ensure that when you get to the hearing you put emotions to one side - I certainly wouldn't use words like "false claim" and "waste everyone's time", you should be calmly putting across your points, ensuring that each one you make is backed up by applicable evidence. The signage isn't great, but it isn't entirely non-existent, so on those points you'll need to focus on why the signage present was insufficient.
If you believe costs are owed, you could take with you on the day a simple costs schedule. The bar for unreasonable conduct is high - I'd personally be surprised if a judge took the view that Excel's conduct (or that of their solicitors) met that threshold, but if you win there is little harm in asking.