This reminds me of the French newspaper lemonde.fr, which I had subscribed to, and then wanted to unsubscribe after a couple months. There was simply no way to do so online, not to reach any customer support. The only option was to send a letter via post. This was during our first lockdown in UK, so no way I would go to the post office for that. I'll simply never be a customer again.
Ha! I had this experience years ago. I subscribed in college to practice my French, but ended up wanting to unsubscribe because I had more important uses for the money. Sure enough, I had to use my rudimentary language skills to write a letter to unsubscribe and mail it off to France.
Personally, I stopped trying to write such letters after a couple instances where the recipient company claimed they never received any letter from me.
Then I learned you should always send a letter with a signature to have a proof of reception, which is a bit more expensive. And then one kept charging me anyway, and still claimed the letter didn't reach the right department (after more time spent on the phone with them).
Bottom line is if a company wants to make it difficult for you to leave the relationship with them, there are tons of tricks in the books for that. Therefore I blacklist them after any sign of dishonesty.