Hi @Anonymous,
Do you want to concatenate the comments that based on the date and enquiry type you selected?
What data source do you use?
I use Table in Excel to test.
You can try the following workaround.
Data Source:
Format it as Table and name it Table1

App Test:
Add two dropdown controls and rename them aas Dropdown1_Date,Dropdown2_EnquiryType,add one listbox control and rename it as ListBox1_Comments, add one label and rename it as Label6_ConcatComments.
Dropdown1_Date.Items: Distinct(Table1,Date)
Dropdown2_EnquiryType.Items: Distinct(Table1,'Enquiry Type')
ListBox1_Comments.Items: Filter(Table1,Date=Dropdown1_Date.Selected.Result,'Enquiry Type'=Dropdown2_EnquiryType.Selected.Result).Comments
Label6_ConcatComments.Text: Concat(Filter(Table1,Date=Dropdown1_Date.Selected.Result,'Enquiry Type'=Dropdown2_EnquiryType.Selected.Result).Comments, Comments & "; ")

Result Test:

Hope this can be helpful.
Best Regards.
Yumia