I am pretty sure this is not the place to post but I cannot get through to anyone over the phone for the last two days.. voicemail box is full and the email option simply won't work for me.

I recently bought a complete competitive playset and I was sitting down to organize and found some random card missing. I am curious if there is a way to get one sent to me or am I having to go buy another expansion for the 1 card?

Forums is not the place to ask as FFG reps rarely come here and those that do won't be able to help.

Goto customer service site, https://www.fantasyflightgames.com/en/more/customer-service/

then select Damaged/missing components which takes you to: http://parts.asmodeena.com/ Fill out the webform. Wait by your mail box.

I would note that if you bought the complete play set from another player and not as sealed product, I would not expect FFG to replace the missing cards. They may still do so, because they're generally awesome about such things, but they certainly have no obligation to replace cards that were likely not missing in the original packaging.