Frank's sporting goods agrees to deliver 20 basketballs, 20 pairs of sneakers and 20 warm up suits to New York Knicks and which are to arrive no later than October 1, in time for the Basketball season. By October 16th none of the equipment had arrived. New York Knicks went out and bought similar products at 50% higher price, and sues Frank's sporting Goods for the difference. Frank claims that the basketball coach of New York Knicks. had orally agreed to permit delivery on November 1.

Is the alleged modification valid?

what if it was contract was for real estate?