MGTS, forget about me forever!

This story is as old as having a permanent telephone connection in our house, that is, since 2005. With a different frequency, but rather regularly they call us from MGTS and offer an internet connection. I refuse. The cycle is repeated.
At the 10th time, I begin to pour out irritation on innocent operators, feeling uncomfortable and, however, realizing that it is also somehow wrong to remain silent.
And the calls are repeated from month to month, and my requests not to call are ignored . At the same time, I am fully aware that there is a certain distance between the operator who changes his work in a few weeks and the exclusion of me from the spam list , which the operator does not pass by suggestion. However, it is very unpleasant to feel that your protest is not put into anything.
Given that I am fairly tolerant of email spam, a phone call still distracts a lot more mail, which already gets into the spam folder.
I want to ask the Habra community for advice on what to do? Write an email somewhere in the "feedback", so who will read it? Send a registered letter? In general, do they have the right to do so, contrary to the request not to disturb their calls, or do we need a formal protest?

The last straw that broke the patience was the call today, on Saturday.