Here is the Scenario:
You have 3 Contracts, now a CEO is calling you saying they immediately need Goods from you and you actually happen to have them. However because u already have the maximum of active Contracts all you can say is: "NO" .
3 Hours later the Shipment for one of the active Contracts is sent and you only have 2 active contracts left. Ugh. If only i could have told the CEO to wait 3 measly hours!
Solution:
When a CEO calls you for an "Emergency Contract" there could be a simple option to say: "Postpone".
As it is an Emergency Contract you could not Postpone it forever but for 24 hours/one full day.
After 24 hours the Player will be asked again if he wants to take this contract. If there is still no Space for new Contracts the Contract will expire and the player will loose a bit of reputation or money for wasting the CEO's time.
If there is Space for Contracts left the Player can accept the Contract.
This way the Player gets the chance to fulfill the Contract if the Player knows he can handle it and has the capacity, just happened to be asked with very bad timing.