Contact

One address, read by a person, answered within two working days. There is no ticket system and no bot.

What to write about

A problem with a purchase — file did not arrive, file will not open, charged twice. See the refund policy for what happens next; delivery failures are refunded in full.
A figure that looks wrong. The most useful message this address gets. Send the program and what the vendor's page says now — it gets re-read and corrected, and anyone who bought can ask for the updated file. If we misread the page, the directory is yours free.
A program to add. The submit form is faster, and listing is free and never for sale.
A privacy request — see what little is held.
A vendor correcting their own listing. Welcome, and it changes nothing about what gets published: the figure comes off your public program page either way.

What this address is not for

Paid placement, sponsored listings, and "improving" how a program appears. No vendor pays to be here and none can pay to change what is published about them — that separation is the entire value of the directory, and it is not negotiable at any price.