Vodafone India — internet recharge

Address:

Bongaigaon, Assam, 783370

On 13th aug 2017, I made a recharge of rs-347 which was on my offer that i'll get 56 gb data for 56 days. but after the recharge the amount get transfer to my main balance & I did't get the recharge, after that I called customer care and they said it was a technical fault, there is no such offer for u, and than after i talked to them, again checked my offer which still shows, that offer. now I want to know why that happen, how can I get my money back ?...coz I was forced to use data from my balance which cost me aprx 300 for 50-60 mb data.