Currently our exchange providers are BitcoinVN, Exolix, PegasusSwap, SwapUz, and WizardSwap. Regarding the extra fee, we're just starting out and want to test the waters - and we'd say currently our main advantage is our user interface and ease of use.
You should have made this clear somewhere. There are users who want to avoid some of these exchanges, and in the end, they will end up with them again (with an extra fee).
If as an aggregator, you mediate transactions in some way, you must be as transparent as possible.