Using keypad to input credit card number

Making a holiday booking by phone, I’ve been asked to input my long credit card number on the keypad

(iPhone SE new)

My phone shows the number above the keypad, but as a phone number, does not beep as usual, and nothing goes through to the holiday company. This is the third company I’ve found asking this, the first one worked, the second didn’t, I gave my number verbally, and this one is not allowed to take the number verbally.

Apple support did not seem to understand what I was describing, took my VPN website security off, said if that didn’t work the fault was with the company’s IVR settings. It still didn’t work.

I’m now waiting for the holiday company to contact me.

Comments/ideas welcome