I am really sorry to hear that. Documents lack authenticity is a very serious matter. It is not only with your employment letter copy or IELTS copy but it is rather something related with your educational documents though. CHC found something suspicious while running a background check on you it could be any can't say specifically. However, sometimes this matter could lead applicant to banned for couple of years, I must say you are lucky. Double check all your documents and re submit your file only if everything is proper. No offence to no one, I would never apply for visa if I have any forged document.