I work for Balmain Hair and we offer HABIA accredited courses. We also partnered with HABIA to create a training manual to help not only with training, but to refer to after training too!
All our educators start as experienced extensionists and are trained by us to the highest standard. We teach planning, placements, application, safe removal, re-application, cutting and blending techniques with hair extensions - all of which are extremely important. Cutting/blending techniques are different with hair extensions than normal cutting techniques. To make them look natural you have to be taught the correct way.
When looking into training you really have to make sure you get it right. If you get poor training you will never be able to offer a premium service to your clients. Hope this helps!