What do you do when a master promises to reimburse you for a cost incurred at his request, then not only fails to repay, but also refuses to even respond to polite requests?

Does anyone have any suggestions? - what is the best way to ask for monies back, and should I expect to get it back? Am i asking too much to be reimbursed?

i wonder also...since this master has always proclaimed himself as "Honorable"... if this bothers him in the least?