Matching a checkbox caption to a cell's value
Anywhere there is repetition, there is a function screaming to be born. What is not clear from your code is whether all the same cells are changed (i.e. eRow is the same in all 30 cases) but I will assume this is the case.

Sub HandleCheckBox(SomeText as String, OtherText as String) 'no need to return anything
    Dim tempBool as Boolean ' lousy name, but this is just to shorten code
    Dim eRow as Range
    Set eRow = Sheet3.Cells(Rows.Count, 6).End(xlUp).EntireRow.Columns.Offset(1,0) 
    tempBool = CheckBox29.Value
    eRow(6) = TextBox1.Value
    eRow(7) = ComboBox1.Value
    eRow(8) = IIf(tempBool, CheckBox29.Value, "Sales Call")
    eRow(9) = ComboBox3.Value
    eRow(10) = TextBox2.Value
    eRow(11) = TextBox3.Value
    eRow(12) = TextBox4.Value
    eRow(13) = ComboBox4.Value
    eRow(14) = IIf(tempBool And CheckBox1.Value, "Yes", "No")
    eRow(15) = IIf(tempBool, ComboBox6.Value, "-")
    eRow(16) = IIf(tempBool, ComboBox7.Value, "-")
    eRow(17) = IIf(tempBool And CheckBox2.Value, "Yes", "No")
    eRow(18) = IIf(tempBool, ComboBox8.Value, "-")
    eRow(19) = IIf(tempBool, TextBox5.Value, "-")
    eRow(20) = IIf(tempBool, TextBox6.Value, "-")
    eRow(21) = IIf(tempBool, TextBox7.Value, "-")
    eRow(22) = IIf(tempBool, TextBox8.Value, "-")
    eRow(23) = ComboBox5.Value
    eRow(24) = SomeText
    eRow(25) = OtherText
    eRow(26) = IIf(tempBool, TextBox9.Value, "-")
    eRow(27) = IIf(tempBool, TextBox10.Value, "-")
End Sub   


Now all that is left is to call it.

You could do this in a series of calls

'[... Your main sub ...]
If Checkbox3.Value then HandleCheckBox CheckBox3.Caption, TextBox11.Caption
If Checkbox4.Value then HandleCheckBox CheckBox4.Caption, TextBox12.Caption
'[... Rest of code ...]


Or perhaps in a series of handlers

Private Sub CheckBox3_Change()
    If Checkbox3.Value then HandleCheckBox CheckBox3.Caption, TextBox11.Caption
End Sub


Or perhaps in a loop

For j = 1 to 30
   cbNumber = j + 2
   tbNumber = j + 10
   If Controls("Checkbox" &amp; cbNumber).Value then HandleCheckBox Controls("Checkbox" &amp; cbNumber).Caption, Controls("TextBox" &amp; tbNumber).Caption
Next j