guidance and advice

Good morning community, I want to know about the experience that many of you have already had regarding online credits. I asked for 12,000 because the advertisement claimed a very low rate of 0.2%, but they only gave 8,040 for 7 days. On the last day of payment, they told me with a strange number that I had to pay 12,024 KZ, almost 50%. The account in the app is different from the account that sent the money. I asked for an IBAN, they say payment can only be made through the app. Because they have hidden interest. How to proceed? Is it possible that if they are not acting in good faith, they can hack the account to withdraw any money that enters your account?