I'm sorry to hear about that. Do they offer visa debit services in your country? I don't have a credit card either, so that's what I'm currently using to buy the coins.
With virtual visa debit all you need is a chequing account. Whatever you purchase will be withdrawn directly from that chequing account. It can only be used online though.
You don't borrow money from bank (no money in your chequing account -> no purchase) so it's really easy to get one.
This manga is so awesome , I wish it can be updated here ( I wish I could buy the coins so that I can read it at lezhin but I don't have a credit card ┗( T﹏T )┛ )
https://www.lezhin.com/en/comic/save_me