Late Payment of Commercial Debts

Excuse 20: It was someone else's fault

Applicability

We have had the odd occasion where someone else was to blame - e.g. the suppliers of the accounting software had a problem that stopped the customer sending any payments for a week while they fixed it.

Underlying reasons

Customer relies on some third party, and they were let down
Customer may be reliant on some third party supplier, e.g. accounts system, bank system, etc. This is made worse if the customer chooses to only give themselves a short period in which to send payment, e.g. doing nothing on a 30 day term invoice for 28 days, and then make payment. Maybe they should allow themselves more time to pay.
Customer does not believe they have an obligation to adhere to the agreement they have made
Customer probably has a fundamental misunderstanding that they don't have to take responsibility for what they agreed to do, and that blaming someone else somehow removes that responsibility.

Resolution

This is nice and easy - if a third party has let them down, then they should pay the penalty, as per their agreement, and pursue this consequention loss from the third party supplier. This is no different to the third party letting them down in any other way and causing them costs. Obviously if they have entered in to a contract with their supplier which does not allow for such costs to be recovered then this is their loss - perhaps they need to consider insurance against such things.
Either way, how is this our fault?