State Bank Of India [SBI] — uncredited amount

I have cancelled a ticket in indigo airlines.They claim to have refunded the entire amount in three installments to my designated account, also they have provided me with three ARN id's to prove the transactions. when i asked the branch to check the details of my transaction they had some process done to check, after that process they said the enquiry says that the amount has been credited to the account .on successive complaints by me they had been enquiring again and again it has been months since the complaint. so i would ask you kindly to look forward and rectify the issue.i hereby provide the transaction ARN id's.
ARN1:IXGAG2JOB5
ARN2:IXGAHANPE2
ARN3:IXGAHCFGK1