Write to contact@kalytia.com. One person reads that inbox, usually within a few days.
Corrections
If a number in an article looks wrong, say which article and which figure. The raw outputs of every test are kept, so it can be checked. Corrections are made in the article itself, with a dated note saying what changed.
If you make one of these tools
Messages from the people who build these tools are welcome, and every one is read. No test can be promised, and no date. What is accepted and what is refused — payment, briefings, free accounts, editorial input — is set out on the Affiliate disclosure page. If your tool is tested, you will read the result at the same time as everyone else.
Suggesting a test
The most useful message you can send is a specific question you could not answer before buying. Those become articles.