The Courier Guy - Slow and arrogant beyond believe

I made an online booking by first obtaining the quote and then paid the correct amount. A day later, and email arrives stating that the account is overdue - How can that be? They held on to the package due to the 'overdue' account. It's now 10 days later and I'm still without the delivery! I've followed their procedures, paid them and now this. After taking it up with customer services, they will credit the account, but only in three days' time.....wait....wait.....fast delivery! This is the second time this is happening to me. I find The Courier Guy arrogant beyond believe.