There are delays at a few of these training schools due to a lack of Instructors and they simply can't cope with the present demand. Airline tagged schemes are also suffering by the way. Just look at the situations vacant pages on their respective websites and in Flight Training News where you will notice there is a general shortage of Flight and TKI Instructors. At least they are delaying your start date before you are forced to sit and wait for months during your course untill a slot is available for you to complete it. I do think these schools should do the right thing and come clean with you as to the correct reason you are facing these delays however.