Yes. They are wrong. Most of the consultants do not have basic knowledge about certain things. They just give some wrong information without knowing. Educational credential assessment in canada website says exactly Diploma (three years) equals to "Bachelor’s degree or other programs (three or more years) at a university, college, trade or technical school, or . other institute"
If It is a Diploma (three years).You should select "Bachelor’s degree or other programs (three or more years) at a university, college, trade or technical school, or . other institute" in express entry. You do not need to ask any consultancy. It is so clear.
Before most people got Canadian Equivalency as Secondary school diploma and diploma (two years) for 3 years diploma after 10th. But You got Canadian Equivalency as Secondary school diploma and diploma (three years). May I know How you got diploma (three years) for 3 years diploma after 10th? Could you please tell which board you completed the diploma from? I completed three years of Diploma from State board of technical education and training in Andhara Pradesh.