Term of contract -contract law

Justin makes tents and he advertises on his website as being waterproof and east to put them up. Marie owns an outdoor equipment shop and sees the advertisement for Justin's tents She buys 1000 tents for Rm 40000 .The tents are very popular and Marie soon sells 100 .Within a week, customers are bringing the tents back because they let water in and hard to put up.
Explain how the Salsa of Goods Acts 1979 will apply to Marie

I'm not a lawyer, but my understanding of this law is that, according to what they were advertised as, these goods are not of merchantable quality and Marie must refund her customers. Justin would the have to refund her.

However, others are much more qualified to answer this.