Credit block active on Customer invoice payment day & also on credit limit

Dear Expats

We have received one requirement from USER. below is detail discussion

Primary info 

Customer ZZZ

Terms of payment - 45 days

Credit Limit BDT 1,000,000/-

Example

First invoice

1) One customer invoice made BDT 500,000/-

2) Invoice date 1st January 2014

3) As per payment terms - Payment due date 14th Feb 2014. (45 days credit)

4) No payment made till 20th Feb 2014.

5) Overdue status - invoice one.

Second invoice

1) Second invoice made BDT 500,000/-

2) Invoice date 20th Feb 2014.

As per above case user requirement is below.

1) Though second invoice is within Credit limit BDT 1,000,000/-

2) System should lock the second invoice - not release.

3) Because -he didn't pay first invoice amount BDT 500,000/- within due date (45 days)

Any invoice not paid by customer within 45 days - system will block though he has approved credit limit.

How can we configure the two indicator as credit limit consideration process.

Regards

Tarek H Chowdhury