Changing Internet provider

There are so many ISPs, ways to connect (and also regional differences), that it is difficult to advice from afar and without knowing your situation in detail.

But as you can certainly imagine, weeks without Internet are not acceptable to anyone. I am sure you can find a way, by containg the providers hotline or shops frequently, to switch without (orwith minimal) downtime.

However, comparison portals show that ISPs generally have very bad customer service ratings (1&1 is slightly better than Vodafone and Telekom, regional ones vary). So this might require lots of stamina - and of course German language skills (get help by a native speaker friend!).

But you cannot blame anyone for signing a contract without reading and understanding it (which then includes TV, which you didn't want). You must learn German to make life easier here!

Wow, sounds like mass confusion. I am assuming you are referring to Vodafone internet access rather than data transfer for a cell phone - also provided by Vodafone. And yes they often bundle TV with internet. It got more expensive for me a couple of years ago as well (also by Vodafone) because they said they were discontinuing the digital TV service previously offered through my DSL connection. I switched to fiber-cable which they sold as being more reliable and faster etc. and now with TV service. I see no difference to be honest but pay more but I am not a gamer so don't have high volume streaming needs.

But there should be NO interruption in service if they make a new contract – unless possibly changing to another company. And even then this is not normal.  This would obviously be unacceptable service. But I think you have likely misunderstood your situation. The contracts standardly run for 2 years and then get renewed, unless one cancels or changes something. One has maybe a 30 day window of opportunity to change tariffs or conditions but then one is locked in for another 2 years! That you can just cancel anytime now with 30 days' notice is (unfortunately) simply not done by any providers in Germany.

40 Euros for a flatrate is not super cheap. But another question is if you have a landline telephone included since this is also often bundled together.

Vodafon is really pushing fiber-cable where it is available. One can have 1000 Mbits/s flatrate and flatrate landline telephone for 19.99 Euro/month – the trick is that this is just for the first 10 months and then the price goes to 69.99 Euro/month. But it cost less if one have a reduced speed like 10 Euros cheaper if one has only 500 Mbits or 15 Euros less to have only 250 Mbits.

If one then adds TV then it is also around 25 Euros/month basic price but one can add additional packages of channels making it cost more.

In the end, it really matters exactly what one is getting;  DSL or fiber-cable, which speed, also a landline connection and or TV….