Plumbing Trouble

Saturday, I noticed the bathroom sink in the guest bathroom backing up.

I tried using the plunger but the water did not go down.

I tried removing the sink plug but I could not get it out.

Josh, Jill and Andrew came over to attend Kameron's birthday party so Josh checked it out for me.
He made several attempts to fix (unclog) the drain.
We later would find out the A/C pan in the attic was holding water that was leaking.

So Josh put some buckets in the cabinet

 

and I made several phone calls and tried to find someone that would come out to snake the drain.
A plumber's appt was made for Sunday 1-3pm.

Sunday, the plumber was here for about 1/2 hour and snaked the drain 30 foot down the line.
It was clogged with algae and other dark looking slug due to this sink is also the drain for the A/C line.

The plumber left...but the story doesn't end there.
The next morning I checked the buckets and there was water dripping.
It was a small leak, but leaking water nonetheless.

Monday morning, I received a Satisfaction Survey from the plumbing company.
I let them know the sink drain was leaking from the work yesterday.
They could not send out a plumber on Monday, but someone would be out on Tuesday morning between 8-10am.
The same plumber returned and "tightened" the connections and left.
Saying  I was "Good to Go!"

Sorry to say the story doesn't end there either.
This afternoon I checked under the sink and what did I find but more water.
Slightly less than the previous day, but still leaking.

Doug called in the afternoon and via SKYPE talked me through taking apart
the P-Trap. I cleaned up all the connections and put everything back together.
It's now been 5 hours and No Leak!

In the photo below, I'm pointing to the source of the leak.