Condo association president getting special favors from contractor

Our President was getting special favors from a contractor. This contractor told the Vice President and another unit owner he was constantly demanded extra work in their yard 45 mim to an hour. Another board member was his friend and said he would do an investigation. He did nothing. Several unit owners wanted a special meeting and have the contractor there, but they wouldn't do it. the treasurer just had the contractor write a letter to the board saying he did not want