Sorry, I just read your message, again.
POST is correct. The content-type shouldn't matter.
Not sure what would cause this.
Be aware: we rate limit requests per second in addition to daily requests. You should keep it at 1 per second.
Try, removing the 3 from the lists: {"deals":[["coupon",413453],["coupon",413444]]}
If you want to add the deal_id as recorded in your system: {"deals":[["coupon",413453,id],["coupon",413444,id]]}
We'll return: {"deals":[["coupon",413453,id,status],["coupon",413444,id,status]]}
Let me know if you try this and are still having issues.
-greg