Hi,
Just saw this post.
One of my good friends who traveled by herself once tried this agency... she said it's great and she went to Machu Pichu. She didn't want to pay for a hotel room by herself, so she asked to be matched up with another girl so the 2 of them can share the hotel expense and this agency was able to accomodate them. She said this trip is one of the best she's ever been to and she has traveled more than I have which says a lot.
As far as partying, I don't think they accomodate to "spring break, drink till you vomit, have sex with as many people in a span of 1 day" type of partying... then this agency may not be for you.
But if you're looking for a more adult, civilized type of partying, then look them up. I'm also putting this link here in case someone's looking to travel rather than party.
http://www.singlestravelcompany.com/
Inquire about anything to the person noted.
Good luck and have a safe trip!
.