simple chatbot

i need a simple chatbot
no fancy AI needed

the chatbot will just guide the site visitor thru a reservation site.

would work like this:

Question Yes / No
if yes : please enter number check number against DB
if number is valid : check availability of number in other DB
if available: ask for pers data and print a reservation ticket and reduce the availability in DB
if not available : ask for entry on reservation list.

I also need the integration on an existing site