Conditional Thank You page

Hi,
My client has pointed out a logical problem with your otherwise excellent functionality.

If a customer who has just used a coupon is rewarded with another coupon for that order, there is no end to it and that customer never pays the full price again!

Across the board, that is a MASSIVE loss of income.

What we need is an additional function that is a conditional display of the coupon in the Thank You page and subsequent email.

The simple logic would be thus:

IF
a coupon is used in this order
THEN
display a Thank You page (and subsequent Thank You email) WITHOUT a coupon
ELSE
display a Thank You page (and subsequent Thank You email) WITH a coupon
END

Is this possible please?

Warmest regards
James