Bond period calculation

Sir I joined coal india limited on 18th sep 2010...i have to serve the company for 50 months with security bond amount of rs 50000..(we have signed this bond, so rs 1000 was deducted per month) In March 2012, they introduced a new bond circular according to which we have to now serve for 60 months with security bond amount of rs 3 lakhs.. (we have not this bond but this bond is applicable to all of us and rs 5000 pet month is stared to deduct from our salary ). Our basic is revised and increased after this circular.. In 17th sep 2015, I am going to complete my 60 months service... But unfortunately in 2013 I was not able to do my service for 8 months due to illness.. And for those months extraordinary leave granted to me without pay, as I had no leave at that time.. Now I am selected in engineering services examination.. So I have submitted my resignation to the company with 3 months notice, which will be going to complete on 17 November 2015... I submitted an application to them regarding my resignation that I am going to complete my 60 months service in September 2015.so please refund my deducted bond amount.. But they refuse it, saying that I have not completed my bond period of 60 months due extraordinary leave without pay granted to me. So now I have to pay the remaining bond amount to the company... Sir I want to know that extraordinary leave without pay will be considered as a part of bond period or not?? As I have not found any guidelines or circular regarding this... Please help...