Facts: This is an Oklahoma case.

Responding to an inquiry from Buyer for an underground oil storage tanks, a Seller send a quotation to the Buyer. The quotation listed a price and also the clause "we are not responsible for delays arising from causes beyond our control". Then, the Seller sends the Buyer an invoice containing description of the materials and a delivery date. These are the only written documents.

The Seller did not deliver on time and the Buyer suffers loss in maintaining a dug hole, extra laborers and the penalties for being late.

At trial, Seller was able to show the written documents and the delivered tanks.
But, Buyer was able to show evidence of several oral conversations -- one at the time of initial quotation and the other at the time of issuance of the invoice. The oral conversations show:
(1). Buyer's acceptance of the quotation was based on the Seller's promise to deliver the tank in time for Buyer to compete the installation of the oil tank on time;
(2). Seller assured Buyer that Seller would be able to do so on time;
(3). Buyer paid a premium on price for the tank;
(4). Seller knew the tank would not arrive on time when they told Buyer the tanks were on the way.

After a jury trial, the jury awarded Seller about $45,000 for the tank but also offset that by an award to Buyer for $38,000 for damages suffered by the Buyer.

On appeal :
Seller argues: The written documents contain all the terms and oral conversations should not be admitted to change the documents.

Buyer argues: The written documents are not final written documents and do not contain all the terms. The oral conversations should be admitted to show the substance of the parties' agreement.

Questions:
(1) Who is right?
(2) For Buyer's side - Unfair not to be able that Seller tricked Buyer. Seller may not be excused by the "not responsible clause"
(3) For Seller's side- Unfair to have oral conversation change written documents. The documents show writing of "not responsible".

Conclusion:
Rule the oral conversation should be admitted. The Buyer accepted the quotation orally and the conversation contains the promise to deliver on time. Therefore, it is a counter offer with the condition that the tank be delivered on time. The jury has grounds to believe the buyer and thus correctly rule on the damage for buyer.