As I'm sure you already know social profile links are the latest backlinking craze for internet marketers.
You could go onto any internet marketing forum and see the seemingly endless amount of marketers selling their services.
You've got people selling 500 or 1000 social profiles for like $50, $100, etc.....
My recommendation is that you don't use them.
It's not that they won't offer a quality service. It's just that you don't need them.
I use an excellent software called Sick Submitter that's really inexpensive ($19.99 a month) and it gets me an unlimited amount of social profile backlinks in an automated manner to all of my websites.
I made the video above showing you how the process works.
What I like best is that it's very simple to use. You don't have to be techie to be able to use the software. All of tools are pretty standard and self explanatory.
Personally, I've been sending thousands of links to both my sites and links that I have pointing to my sites to give them more link juice.
The customer support is excellent. The couple of times that I've emailed them, I got a response within 24 hours.
Although, you don't really have to contact them directly. Support is always in the forums, you can just ask a question there and they'll answer it really quickly.
As far as finding the forums to submit to, there are a TON of free sick packets (files with forum links) that are on the forum. You can also pay for sick packets which usually have more forum profiles that you can link to. They are not expensive. They are usually around $10-$20.
I normally notice a resurgence in SERPs usually within a couple of weeks after I submit a batch.