Update:
In the meantime, I have found out that the receiver for my presenter (type R700) has the designation "C-U0014 and the article number P/N 993-000911. The receiver can be ordered on the Logitech website. Considering the circumstances (creating a new account, shipping costs, etc.) and that digitec carries quite a few Logitch products, would it not be possible to order the "part" via digitec?

Had the same problem. Unfortunately, you can't buy them separately. I would recommend the Logitech Spotlight, which has Bluetooth and a battery.