I am failing to get tag value from the firebase data base



I am trying to retrieve data from the tag value which is combination of phone number, date and time. I want to vomit time as the time might not be exact to query to get data, but kept it as if some one enters data on the same time, old data is over written. I want data from the data base which when inquired with phone number and date it should return particular data of the phone number ad date . pls help me out. struct since many days.


This is the block i am trying with