Unsolicited change in internet connection

My internet connection package was Tango Fibre L (at Eur 49.99 + Eur 4.99 for communication package). In May 2021 this was changed automatically and without any explanation to Tango Fibre M (at Eur 54.00 + Eur 4.99 for communication package).

Can you kindly explain why my internet is now more expensive and less performant? Why aren’t such changes communicated to the client?

I have already written to you three weeks ago (if not more) under case number **** . My question on this point was ignored.