Here is a method that lets you find the errors.
Dim strSQL As String
strSQL = "Update Telecalling_database set Calling_end_Date_time = " & Me.timer1.Value & ", Paid_Unpaid_Status = " & Me.Paid_unpaid_status.Value & ", No_of_Premium_Required = " & Me.No_of_Prem_required.Value & "...