the case of business law how to solve this case

the case of business law how to solve this case
Harry and Gabriela (‘H & G’) decide to host family members and close friends at a dinner party in their home.They decide to engage the services of a commercial caterer to provide food and drinks.Harry’s Aunt,Paula (‘P’) suggests an Italian couple,Johnny and Natalia (‘J & N’),who she claimed are very good caterers.H & G decide to engage the services of J & N.P arranges a meeting in her home between H & G and J & N.Both couples meet to discuss requirements for the party.When asked about dishes,H & G say they are flexible and willing to accept J & N’s recommendations.J & N nominate three courses which H & G accept.J & N also suggest that H & G purchase all salad ingredients and they (J & N) will either freshly produce or purchase the remaining ingredients.When asked how much their services would cost,they replied:
“You pay us after the party.If the food is good on the day,you pay.$1700,$1900,whatever,you pay.”
H & G inform J & N the party will start at 1:00 PM and food service will commence at 1:30 PM.After the party,J & N forward an invoice of $2,500 to H & G.H & G refuse to pay the amount making the following claims:
a.That J & N were late on the day and food service was delayed;
b.That food served was not of good quality.
Advise J & N as to their rights and obligations under contract law in relation to H & G and P.Give reasons for your answers.
这个case 是condition 还是warranty

warranty
这个case关键点,在这个contract是否valid
Paula是否为第3party
late 是condition or warranty
这个在law and business 书上P108下面有.就是How do courts determine whether a term of the contract is a condition or warranty.
参考下面的case,Tramways Advertising pty ltd v luna Park即可