How to automate checking all responses to a form on a website?

I would like to check all options on an airline website. So I would like a script or service to:

• automatically log in
• choose the departure
• the destination
• the date, etc.

I then needs to click some pop-ups and check the response. The site gives an error if it finds no seats, so it should be easy to see if a positive result is found.

It then needs to increment the date and try again.

I have tried Selenium, but it seems to struggle with the website when I was recording. I have also tried Screenster, but it seems it will only state if it finds errors.

Anyone have ideas or software I could try?