Yes, it happens. I also tried to top up my account via card at one time, but there were also delays. Since then, I switched to e-wallets - they work faster and without failures. By the way, now I do everything via a mobile application - it's easier to control the balance and quickly top up the account. If you're interested, you can take a look at https://pin-up-bangladesh.net/app/ there is a convenient interface for topping up via different methods.