Bad quality bikini

We bought a bikini. promising that we would received it in 2 days, but in the end after 5 days we had to fetch it at the currier company. receiving the bikini it already started to unravel at the one side but it was very small and left it. after only one swim it started to unravel everywhere. after I complained about it they told me that they do not do long term guarantees!<br> If I pay R400 for something I would expect it to last longer than one swim!<br> <br> I need to get this exchanged for a better quality bikini or my money back.