Protect my Excel Work

[thameralqershi]

Hi all,
Actually my topic is more than just a quesion.I have passed lately through a bad experince where is one of my returning customer asked me to do him some vba and macros work and finally, he got the job after accepting my offer and refused it after that saying it has some mistakes and dissappear. He refused to answer my messages "through Fiverr for sure:
So, I have 2 questions here:
1- How can I protect my Excel work? It is not like designing gigs whereas you can add a watermark to grant that no one will seize your work for free.
2- How can I deal with such situation? Now, this wonderful person get the job for free and he will downgrade my order completion rate. and I am sure that he will do that with other experts in future. Note that I have talked to fiverr. However, their responce was negative saying try again with the buyer maybe he will answer your messages.

Thank you
Thamer