Damage whilst tenants moving out - who is responsible ?

Maintenance

Hi
My tenants have recently moved out after 18 months. Whilst moving out they damaged the laminate flooring in the bedroom. My builder has tried, in vain, to reposition the damaged boards under the wardrobe. I have driven all over to try to buy similar laminate to patch it but have not been able to find the same colour, and more importantly the same size as the existing laminate.
I have therefore obtained a quote to replace all the boards in the bedroom with new laminate or carpet. The carpet is the cheaper option, but obviously won't last as long as laminate. I have put it to the tenants that they will have to pay for the new carpet out of their bond, £160, and I will pay the builders invoice for the time spent on trying to reposition the laminate and then ultimately take it up. I haven't charged them for my petrol or time for the 3 hours driving round every laminate shop in the area. I also have charged them to redecorate the bathroom as they never opened the window or used the dehumidifier I provided.
The tenants are arguing that it is not their responsibility to pay for the carpet.
I have said that had they not damaged the laminate whilst moving out, I wouldn't be replacing it at this time.
What does everyone think please?
Thanks