Group By needing help

Try this code Anon29 

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("lZM9D4MgEIb/imE2kQNEHUuHDk2njsYBGweTph+mDv33Reyg9a6B5SDk4fLe3Xt1zUSV8TITXEiWsr19JYd+uLqrbS/g3xSAixXnrEmDcOVisoXP46MbNrj22YXKwz+IuPwSx3HtOgYucNg4+GRvS7b0VYayU4E6R/qN0kS7UZYob/ccbWLu7yUMQGkmaGIsBD0dUofWWMZ0muPwsVuBIL/OQzSQViW8hOv469MfHOY9UNiWGTu0fbeiC9pPCDsJkcGZI/ZFzB7xc2w+", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Date = _t, Agent = _t, #"Talk ID" = _t, Talkorder = _t, #"Stat (seconds)" = _t]),
    #"Changed Type with Locale" = Table.TransformColumnTypes(Source, {{"Date", type date}}, "en-BS"),
    #"Changed Type" = Table.TransformColumnTypes(#"Changed Type with Locale",{{"Stat (seconds)", Int64.Type}}),
    #"Added TalkOrder Group" = Table.AddColumn(#"Changed Type", "TalkOrder Group", each Text.Start([Talkorder], 2), type text),
    #"Grouped Rows" = 
        Table.Group(
            #"Added TalkOrder Group", 
            {"Date", "Agent", "Talk ID", "TalkOrder Group"}, 
            {
                {"Stat (Seconds)", each List.Sum([#"Stat (seconds)"]), type nullable number}, 
                {
                    "TalkOrder ID", 
                    each 
                      let
                        varTalkOrderLen = Text.Length(_[Talkorder]{0}) -1
                      in
                      Text.Start(_[Talkorder]{0}, varTalkOrderLen)
                }
           }
        ),
    #"Removed Other Columns" = Table.SelectColumns(#"Grouped Rows",{"Date", "Agent", "Talk ID", "TalkOrder ID", "Stat (Seconds)"}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Removed Other Columns",{{"TalkOrder ID", type text}, {"Stat (Seconds)", Int64.Type}})
in
    #"Changed Type1"

It returns this:

What the code does:

1. I added a group ID that is just the first two characters to it groups by 41, 61, etc.
2. Within the group, I find the length of the first Talk Order ID for that Talkorder ID grouping and subtract 1.
3. I then truncate the talkorder ID by that length

How to use M code provided in a blank query:
1) In Power Query, select New Source, then Blank Query
2) On the Home ribbon, select "Advanced Editor" button
3) Remove everything you see, then paste the M code I've given you in that box.
4) Press Done
5) See this article if you need help using this M code in your model.