Dear {Recipient},
I am terribly sorry about our use of your material, {Name of Work}, in our project, {Violating Material}. I was unaware of your copyright, and due to an oversight, my company used your materials without your permission. However, we would like the opportunity to make this right with you.
We are prepared to offer you a sum of {Offer} in order to gain permission to use the materials. Alternatively, we can pull our entire project from circulation and remove your copyrighted material. Please let us know your preference as soon as possible by contacting us at {Phone/Email}. We are looking forward to making this right with you.
Again, please accept our sincerest apologies.
Sincerely,
{Sender}
