I am writing a business letter and I would like to bring it to a directing manager of another company's attention that as far as I am concerned, unfortunately I do not feel good, and I want to refer to some fishy activities and some immoral, dishonest and fraudulent business dealings of some people who are interfering between the two company's business affairs (mine and his companies) and mention that for some reasons they would like everything not to work properly. No matter how, they are trying to make their own benefits and they are acting up. (Consider them as some people who were trying to achieve this business prior to the contract between the owner of that company and I and at the time being they are green with envy). In such cases we say:
I feel there are some concealed hands in the story.
I feel there are some people behind the curtain.
I hope I could make myself understood. If so, please let me know what shall one say in the identical situation (not only in a very formal business letter, but in everyday conversation; because I am not looking for something too formal.)