I used them few years ago, perhaps things might be changed a bit but here is the overall:
Main contact with the bank is over emails, you create an secure email account (Symantec Web email system) and send and receive mail thru that. So as far as I am aware there is no phone contact. They were fast to respond. They introduced 2FA feature quite late to be honest but they now have it. Back then you had to sign documents physically and send it by post (maybe nowadays it's all electronic), this was before Covid times (like 2017-2018 I guess).
My main issue with them was, you need to open a new account for each currency, and you can send money to that account only from your reference account. So if you close that bank account of yours, it's not possible to cash out your money from Easisave account as they do not have a feature to change your reference account. So if you send monies from your PTSB account, and close that PTSB account of yours, good luck recovering that money from Easisave.
I got in touch with them about this (as it happened to me) and they asked bank statement showing that the account is closed or a letter from bank saying account is closed. For me, PTSB never sent me final closing bank account statement so I couldn't prove them with such document. After few emails and like a week later, they agreed to send my money to my new bank account. Even thou the balance wasn't much (like 10-15k) it stressed me out a lot if my money got stuck with them.
After this incident, I didn't use them again, as their rates are not super special, compared to what other banks or brokers offer nowadays.