Before sending funds to trade on your centralized exchange, always check at immediate time If the exchange still allows NGN (#) P2P because the way naira is been scrapped off from the P2P feature is overwhelming.
Ignorant to do this verification before sending funds from your self-custodial wallets to the exchange wallets will always cost you excess expenses on transaction fees from an exchange to another before you could realize yourself and call it mistakes.
You came up with a nice suggestion and advice, but any one that is very vigilant on what he is doing will not just send his funds to exchange without checking, especially if the person is in this forum, because any time an exchange removes NGN p2p, they will definitely bring the discussion here in the local board, so even if you don’t do research, you will see it, and moreover, many have started understanding to check even though they have no USDT or bitcoin, so it is simple.
Furthermore, if you even made that mistake, you can still send your USDT out without any transaction fee, so don’t panic. All you need in that serious situation is research and help from people who have experience already, because you can use TON which is even for free, or you can use BSC(Bep20) which has lower translation fees than a dollar, just some cents.