Thanks @June7 done that like so:
strSQL = "SELECT [CustomerID], [Broker], [Lead_Date], [Client_FN], [Client_SN], [Email_Address], [Mobile_No], [Email_Sent], [SMS/WhatsApp_Sent], Nz([Phone_Call_#1], '') AS C1, Nz([Phone_Call_#2], '') AS C2, Nz([Phone_Call_#3], '') AS C3 FROM Client" _...