I discovered a bug in Tesco’s online shop, and sent an email to their “Technical Queries” email alias to tell them about it. Here, approximately, is the exchange:

I said:

If you enter a phone number with spaces in, the submit silently fails.
The problem relates to the fact that the form submit() call is in the final
else() branch of the JavaScript in SubmitFormAddress().
If you have a phone number with spaces in, you enter this branch:

else if (isNaN(document.form1.textdayphone1.value))
{
temp = document.form1.textdayphone1.value;
while (temp.indexOf(" ")>=0)
temp = temp.replace(" ","");
if (isNaN(temp))
{
alert('Please use only numbers for the phone number');
}
}

If the phone number has spaces, the first isNaN fails, but the second
succeeds, and so you don't get an error popup, but then the submit doesn't
get done because it's in the final else {} branch of the big validation
statement.

They sent me an automated acknowledgement, and then said:

Thank you for your e-mail.

You cannot leave any spaces in the phone number or the system will reject
it.

Kind Regards
...

Oops. I’ve obviously hit the wrong technical level. I was hoping for a techie… So I said:

This is the problem - the system neither rejects the number nor submits the form. It just does nothing.

Please pass my original message on to your technical team - they will understand the problem.

After another automated acknowledgement, they said:

Thank you for your e-mail.

There are no current technical problems with our website, therefore, please
call 08457 22 55 33 and select the option for "Technical Assistance" if you
cannot register. These queries are not easily resolved via e-mail.

Kind Regards
...

Did he actually read what I said? I’m not having a problem registering. And “there are no current technical problems with their site”? That must make it unique among e-commerce sites… And they want me to report website bugs by phone? The mind boggles.

I replied to that effect, but as yet have had no response.