what do I do if buyer is just trying to steal my work?

what do I do if buyer is just trying to steal my work?

ORDER?
#74376

I have sold the buyer 10k twitter followers and he keeps rejecting my work.?
He said he the followers that I delivered to his account were from another seller. Basically, he ordered from two sellers and he is saying that the followers didn't come from me. This took me time and money to complete.. but either he bought off two people at the same time or he's just trying to rip me off. I have a link to the whole conversation. Thanks