This was deceiving to token sale contributors, Visa is well accepted all over the world, one thing is having the Visa logo on the card one thing is not having it (including access to the service).
Simply many merchant will not accept the card unless it has Visa or MasterCard on it.
You should give the option to your contributors to receive a refund if they are not happy with this development.
They do have access to the VISA network. And why would you want a refund when you could sell your TKN above ICO price? This is nonsensical...