'But time is now of the essence to reap the reward: this offer closes on Sunday!'

Just had an email about ready to drink burgundy which contains the above sentence. I’m puzzled. The wines don’t seem to be offered at a discount so will they be withdrawn from sale from Monday, even if unsold?

I think they are just using the normal offer document text.
For example the recent Languedoc-Roussillon offer (which also closes this Sunday) has no special offers.
In the case of the Burgundy offer, I suspect those that haven’t sold out by the end of Sunday will either go back into regular sale or be cellared for a future similar promotion.