Reliance Communications — I have not found my security deposit

Address:

781012

My mobile no [protected] rcom i had mnp to other network because of network problem. November 2017 they are told me no problem your security deposit will be refunded to you within 3 month by check it will be send your billing address. So i wait for this long time after 5 month i was went reliance office there office employees checked there system and inform me sir your security mony u get back within one month. Today is 6th of october 2018 i haven't found any cheque or letter from the company so please inform me if any way to get my deposit money back. Please