Ms. Sue, I urgently need you to check this email. Thank you

1) I suppose you received the remaining balance because my bank has already taken the money from my bank account. 2) However, I would be grateful to if you let me know about that all the same.
3) In my previous post I wrote that at the end of August I was coming to pick up my children from your school myself.
4) As I'll busy at that time, I would prefer you to accompany them to Heathrow airport yourself.
5) Furthermore, I wonder if it were possible to receive the prospectus (leaflet) about your summer courses as well as a list of things they should bring with them as soon as possible since I will be leaving Milan in two weeks.

4) As I'll be busy . . .

The rest is fine.