Thank You Letter After Retail Interview Calling After An Interview?

Calling after an interview? - thank you letter after retail interview

Yesterday I had an interview. The interviewer is not the e-mail, but I have the phone in the office. I was told that I am not in a period of 4-5 days, or I have the mandate have been informed.
I read the line that you need to send a letter of thanks or thank you e-mail within 24 hours. I can not send e-mail or letter.

Should I call within 24 hours thanks to the interviewer? What can I say?

PS - the interview was in a clothing trade.