I gave you 2 suggestion for increased followers... 1. Use any tool 2. Follow new followers or follow that followers who has low no. of followers.
If you want to pay for followers Fiverr.com is good. But ​I think by far the best way to grow is by interacting with others - replying, retweeting and posting useful content.
I have a couple of suggestions 1. Quality, 2. Constancy. What I mean with this is, Why you want a huge number of followers, if they do not buy from you, if most of them are spammers or other marketers. Instead of doing that select your niche and put valuable information about it, do not overwhelm, work constantly and every now and them send your advertisement, Quality and Constancy pay best.
Follow software can bring you results but many of those followers end up being spam and very untargeted.
Grow it organically so that the followers you gain will actually be interested in your company, tweet good content, network with tweeters and bloggers that are influential about things pertaining to your company, things like tweet adder are useless because you can rarely turn a profit for the followers you gain because they are people doing the same thing your doing, and are likely spammers.
all software tools is almost same function the important thing is build relationship with all your followers
Relationship rule! Naturally, the problem of targeting is of great relevance to software stuff. So, better less, but better
check out the site in my sig to get quality targeted twitter followers and many other services such as youtube, facebook etc.