Switch to companies that are easier to get ahold of (if your current supplier doesn't allow to change your details online, switch to a competitor that does), and possibly cut down on the number of companies you interact with so the task takes less time.

> In addition, my mail box

Email or physical mail? For email, every time you get receive bullshit, spend a minute to try and unsubscribe. I recommend not using the link and instead logging into the website and unsubscribing from all their mailing lists, where as the unsubscribe link would usually only unsubscribe you from one of their mailing lists.

For physical mail if it's a company you have an account with I guess you could do the same and see if there's a way to opt-out (I imagine they would want to save costs and not spend money mailing out physical spam to someone that isn't interested). For the rest sadly there isn't much to do, but if any spam arrives with prepaid envelopes just put their garbage in there and send it back to them, just to waste some of their money.