Conversion of airtime to cash is what we mostly face, though we have some platform that can convert them they buy from you and send you your cash.
Some exchange in a rate that won’t pay you,some will even buy the card and you won’t see cash while some there rates are bad, so I don’t say you should not trust them or patronize them.
Here I will be giving you best trick on how to convert your airtime but please it only work for MTN users. I swear the trick is %101 Sure, just follow the procedure and get your payment in 10-20mins

See here: https://updategist.com.ng/2020/07/16/simple-trick-to-convert-your-airtime-to-cash-2/