Arrears on promotion from actual date of promotion

I am working in Indian Railways as Chemical & Metallurgical supervisor. I have been promoted to this post with 7 others through a common order from the headquarters. Now each of the 7 candidates work in different Railway workshop. Some of the candidates were posted in the same workshop after promotion while a few including me were transferred to a different workshop. Now head of the workshop CWM did not released me for 4 months and I was working in my original post. While my other colleagues who were promoted in the same workshop immediately joined the promoted post from the same day and started to draw higher pay in the new pay scale. I was drawing old pay scale. I made three or 4 appeals to higher authorities but none of them were replied. CWM released me after 4 months and I joined the new workshop as promotee after 4 months. My new pay scale started after 4 months. The rule given by administration was that increased pay scale for the new post shall be given to me from the date I actually shouldered the responsibility of the new post. Now I applied to CWM of my new place that arrears to be given to me but CWM did not responded. Now I would like to approach CAT for arrear claims. What is the procedure for approaching CAT and what are the relevant sections of IPC and Railway establishment code and relevant court judgements that can be cited? Please reply and please give only the case nos and I can find out from Indiakanoon