Sort/total up invoices in to month...

Hello there......

Please see the attached and i hope this makes sense???
I have a statement i need to send out and along the bottom there are totals for 1 month over due, 2 month over due etc. What i would like to be able to do is have a formula that totals these up for me instead of doing it my self......

I'm sure the attached will make more sense than my paragraph here!!

regards to everyone who looks into this for me!!!

Frazzfreeman