Im sure a message to the company owner would be seen as reasonable and the dead leg would be removed.
I lost all sympathy when the OP assumed that there was 1500 profit in the job forgetting the vat, tax, wages and all the other costs involved in running a company.
There was no need to bring all that into it
Customer: "it took you 10 minutes to fix that and you've charged an hour!"
Me: "No! It took me 20 years!"
