Involuntary Contribution (erroneously prepaid the expense of a web domain)

I erroneously prepaid the expense of a web domain for a non-profit organization where I used to work (after I resigned) and they have refused to reimburse me. Rather than take them to court (the court expenses would exceed the reimbursement), can I just write this off as a contribution? What if the organization keeps the money (as they have also kept quite a bit of my personal property) but refuse to issue a letter of acknowledgement of a donation? At what point can I just report them to the IRS?

[mazBut]

first course for you to follow is send them a 'private notice' narrating your claim and grievances against the NGO, then wait for their reply before letting law in motion. Ofcourse, you should have proofs to substantiate your claim but you needn't furnish the same to the NGO in the first demand note.