Vodafone India — Offer 300mb 3g 5 days but received only 150 mb

Sir, there is an offer regularly in my vodafone no [protected] regularly on seeing *121# for 300 mb 3g in rs 49 / -. I recharged by seller on 22/12/2015 & 0n 26/12/2015 for 49/. but I credited only 150 mb . i tried to resolution by customer care but it was all in wain. this is a bad customer service and unprofessional practice and a cheating with customer by showing offer but not giving proper benefit. it also repels customers from company. so kindly resolve the issue as earlieast as possible & credit my rest MB 150 (22/12/2015)+ 150 MB (26/12/2015)=300 MB.