BE has actually scheduled this exactly as you have specified.
When you choose the Week days options, and schedule a backup of the 1st Mon to Sat, 3rd Mon to Sat and Last Mon to Sat, you are actually getting exactly that
15-18 June - are the 3rd Wed,Thu,Fri,Sat of the month.
20,21 June - are the 3rd Mon-Tue of the the month
24,25 June - are the last Thu,Fri of the month.
27,28,29,30 June - are the last Mon, Tue, Wed,Thu of the month.