I had experienced this in the past where I had sent coins to the wrong address but I was lucky enough that the exchange has recovered my coins. But we all should double-check the address while sending the coins to the exchange.
Many people have experiened this as I read in reddit posts made by different people with the same problem and not one of them replied about getting their btc back from where thet have sent it to. You are lucky that you are able to get your coins back but I don't know what will might happen if you have sent it to a wallet address that you own instead of an exchange wallet address.