How long ago was this?
Why didn't you notice the marks immediately?
So this is mud effectively?
Thanks for the information.
I am sorry but I cannot give you good news then.
I’m afraid that if this is just mud then there isn’t a claim. That does not cause damage. That just creates a cleaning task. Unfortunately people do that all the time. There is no obligation upon a tradesmen not to leave mud stains on a carpet.
I'm sorry this isn't the answer you wanted but it is the position that you face and I have a duty to inform you truthfully.
Hope this helps. Please let me know if you need more information.