Post increase by mail not received – special notice ?

Hello, my insurance company has made a (although small) tariff increase, which is why I wanted to cancel my contract (does not expire 01.01.-31.12). My insurance company writes: “This (Info contribution increase) we have with our contribution invoice by DocuSign-Email on 08.10.2018 verifiably sent to you.” The procedure of the system is the following: You receive an email of the insurance company on your deposited e-mail: “Information about your contract ..” .. you click on a document or unlock it and you will see it. By clicking the document, you can also automatically activate it on the insurance portal. You can then view it there directly after the login. I received the documents by mail from the insurance company at the time and also a few days ago several e-mails to my driven kilometers. So it is impossible that exactly this one e-mail has landed in the SPAM folder. Also on the Porta l of the insurance it is obvious that I have not yet activated this document. So the insurance did NOT inform me by email about the increase of the contribution. Therefore I have a special notice right. Is there already experience here ??