If you make a transaction with your card and do not receive any alert, instantly or at all, by Viber or SMS and/or email, this is probably due to a technical problem of the telecommunications provider to which you are subscribed.
Other eventual reasons:
• The inbox of your email or your mobile phone has exceeded its capacity
• Rules for identifying SPAM messages have been activated and Alpha Bank has not been designated as an acceptable sender
• There is no mobile telephony signal in the area where you are.