Nick Fury ('Fury') is an agent who works for Shield Pty Ltd, a law enforcement company. Fury is skilled in armed and unarmed combat. He was a heavyweight in boxing during his time in the military. He is also a black belt in Tae Kwon Do and Jiu Jitsu. Fury was also a combat veteran in WWII, The Korean War, and The Vietnam Conflict. Shield Pty Ltd hired Tony Stark, an armoury maker, to build a suit of armour to be used for their Special Weaponry section. A written contract was signed between the parties. Tony has a very high-level intellect. He attended Massachusetts Institute of Technology (MIT) and graduated with the highest honours at age 17. He knows almost everything when it comes to science and technology. He is a professional engineer, and can create, fix or tinker with any kind of mechanical device. Tony is famous for creating the best suits of armour that are made out of very strong materials. The suits of armour can withstand heat and blasts and are very durable. Nick Fury told Tony that it was essential that the suit of armour was durable and would last at least 5 years. Nick added that the suit needed to work underwater and in space. Tony replied "All of our suits can be used all over the universe. We have it covered. Our suits will last you more than 10 years." The two agreed on this verbally and this statement was not incorporated into the written contract. The cost of a suit of armour was $500,000, to be paid as the work proceeded and the balance on completion. Shield paid $250,000 while the work was being carried out. When Tony said he had finished the work, Shield ran some tests on the suit as soon as they received it. Nick Fury got in the suit and dived into the ocean. Immediately, the suit's power switched off and it would not turn on again. As a result, Shield refused to pay him, arguing that the suit did not work according to their agreement.

Using common law principles, please advise Shield of their legal rights