Best site to promote music online?

Hi guys. Can anybody suggest to me a good service provider (website) that will help promote your music online? For example you uploaded a track or a mix on SoundCloud and want to get a certain number of plays, comments or likes on it for a fee of course. I know there must be a number of websites out there that do this but not sure which are most trustworthy or reliable.

I would appreciate recommendations from somebody who has actually used service provider(s) like this and is happy with their service (had no problems) so far. I have tried one company so far (it will remain unnamed for now) which has failed to deliver, so I'd like to get some other suggestions.

Thanks in advance.