BSNL Broadband
Rebate on Broadband Erro

I have BSNL broadband connection Home500C from 28th june. My broadband was not worked in time period of 3rd july to 20 july (18 days). I have mad complaint on 3rd july my complain no is 6366458 and my complaint solved on 20th july. So I want rebate on broadband bill for this reason but in BSNL office they simply reject my request for this. Please help me in this matter.