There is a sure thing about article writing business: You will fall into a scammer's project and your hard work will be in his hands. If your client did not pay you within one week than stop working for him and than do the next best thing: START EXPOSING HIM AS A FRAUD. Do it as you must not hope that by keeping quiet about your situation he will pay, because your client will not pay no matter what you do!
You spent your time typing articles and surely you have done it under deadline stress (something close to impossible to be achieved) yet you manage and you finish on time, than surprise, YOU NEVER SEE YOUR PAY.
There is nothing you can do but acknowledge it and move on, is it?
No, you can fight the system and win! Take your articles and sell them! You still own the copyrights so do not be afraid!
As these scamming situations are occurring more often, there is a need to let frustrations out. You have found the right spot to do it. Let people know who scammed you! Do not be afraid to say who was your scammer as he will not pay anyways, but by exposing him as a fraud, he will not manage to scam others!