Beware of Vodafone policy about prepaid flatrates, "Toppings"
 

Vodafone Germany offers its prepaid (CallYa) customers a loyalty program, Vodafone Toppings. Depending how long you've been with Vf, you get extra calls or megabytes when you top up your phone. Vodafone sometimes offers customers a thank-you like a two-day flat rate for Internet use or calling. That's very nice of them, right?

But what they don't tell you is that these are not added to your regular basket of minutes/MBs/SMS. Instead, they are separate bundles that are valid for a short period and have lower priority than the minutes included in your CallYa bundle (e.g. CallYa Smartphone Special).

For example, you have just topped up and Vodafone gives you the "super topping" (currently a day of unlimited internet) as your reward. You currently have 700 MB left of your monthly 750 MB allowance as a Smartphone Special user. So you use 500 MB during that day. Check the MeinCallYa app in the evening - and your main balance is down to 200 MB - even as the "flat" is shown to be in effect.

Or you have another 100 minutes/SMS left in the middle of the month when you top up and receive 100 free. So you talk for 99 minutes - and at the end of the week you have a balance of 1 minute left, because the topping minutes expire after 7 days but they aren't touched until you use up your main contingent of minutes.

In short, unless you are a Talk&SMS customer (with no included minutes or data), you should be very careful about relying on CallYa Toppings - and beware of any free gifts, particularly "unlimited" calling or surfing, that Vodafone offers you.

this problem will cease itself as Vodafone is currently closing down the Toppings loyalty program. No new registrations are taken and the existing customers are phased out in several waves. There will be a new program in place shortly after the Toppings is fully closed.