I favor Das Sajal. Also, the others have put in great pieces of advice. I believe you need a step-by-step action plan, and so this comment.
Understanding the Psychology of a 'Closed Group'
I suggest you look into the psychology of a 'closed group' inside your small company before you let them attack you with written feedback. These are reports you cannot keep for yourself. The next issue might land on your Manager's desk, providing solid proof to confirm action since they did this once and may do it again. In your case, what you should perceive from what Mr. Ramanan rightfully quoted above, "nobody kicks a dead dog," is that someone kicks because they want it dead and out cold.
Strategy to Address Feedback
The best strategy right now would be to step back and acknowledge to your Manager that you have realized what went wrong. Remember to put a big smile on your face, not that of a grounded person, when you say this to him. Thank your peers with a smile for bringing it to your attention in a written statement and close the case now. Buy time.
Questions to Consider
Some questions you need to look into would be: Was your predecessor a much senior female? Or are you a little too young compared to the problematic group? Is your language far too good with structured vocabulary? If any of these are true, that could be a reason to corner you.
Creating a Character Profile
Make a list of the people who have conned you. Call up and talk once again to your predecessor. Get personal feedback in their individual cases and "write" them down. Make a character profile and try to figure out a way specifically for each person before you proceed. Make a checklist of the changes you have brought in the last two months (include everything involving tea breaks or smoking or anything). If you have done this, you might understand who you have offended and where this wave comes from. Now, go to each of them, smile, and spot the ones who avoid eye contact with you. Rearrange the list and group the ones who should be gagged.
Formulating a Strategy
Formulate the strategy based on them and then build this questionnaire as Mr. Simhan said. The questions should be focused on the most likely 'suspects.' Offer closed questions and give them a drop-down list to choose from rather than providing spaces to let them flow. Never give an option like 'Too bad' to choose from. Maybe put 'Needs more attention' or the like. I say this because from what I can see, it is just a matter of time before they will repeat this, and I believe your Manager is not quite experienced with 'IT minds' (forgive me, nothing personal). Unfortunately, some are base introverts, and they react like a black mamba when threatened. They become so because of the way they are forced to think when working in IT. Trust me, I know. Hours and hours of thinking and looming ideas day in and day out, rather than living life in action as it should be. It becomes a habit. Cannot blame. Understand them and work around it.
In a Nutshell
Stand back, acknowledge, learn grounds, spot the key, devise a strategy, talk alliance OR/AND keep an extra eye on the key person, find a reason to hit, remember to cut off all alibi, present your case to the Manager. Even if you cannot manage to push him out, you will have better grounds, for fear is the reason they did this to you. Capitalize on their fear and remember to play it safe.
"Obstacles are like wild animals. They are cowards but will bluff you if they can. If they see you are afraid of them, they are liable to spring upon you; but if you look them squarely in the eye, they will slink out of sight." - Orison Swett Marden
Regards,
RJ
CEO & MD, Microbion
(Ex-Lawyer)