These are spammers who use Bit.ly URLs to mask the URL of their malicious websites. They purport to be a link building service, but in reality they’re just spammers and most likley scammers.
I have a contact form they have been spamming for well over a year, Some of the submissions below as examples. You can find out more about their spamming on Trustpilot
If you have been affected by them you can report their abuse to Bit.ly directly.
Other people have had similar experiences with them. Read more.