Your situation is quite typical, unfortunately. I myself have been caught in such “surprises” a few times, and we need to talk about it, because there are a lot of risks in cryptocurrency transactions. The main thing to remember is that the cryptocurrency market is still not as regulated as traditional financial markets, and this makes it more vulnerable to fraudsters and not always honest services. Let's break down the main risks and ways to minimize them. According to
https://www.blockchain-council.org/cryptocurrency/risks-in-exchanging-cryptocurrency-and-how-to-avoid-them/, fraud through fake exchangers is probably the most popular way to lose funds. Scammers create sites that look like popular exchangers, but in fact they just collect your crypto coins and give you nothing in return. Such sites often have a “too good” rate, which should also make you wary. I always check the reputation of exchangers on forums and specialized resources before making an exchange. Usually good exchangers are not afraid of reviews and have a lot of positive comments. Problems with commission and hidden fees. This is also a pretty common mistake that you can avoid if you check all commissions beforehand. On some platforms you see a “favorable rate”, but in fact there may be a high commission hidden on the exchange, or insufficient liquidity, because of which you get not the amount of crypto you calculated.