Our landlord/landlady have twice made statements that suggest they breached our privacy. We have not recorded our conversations since we understand it would be illegal to do so.
However, we wish to get to the root of the matter and force them to declare how they obtained such information. Our second conversation was over the phone - can we escalate the issue with the hope that the court can summon a recording of our phone conversation (where the violating statements where made) for evidence?
Generally they don't. If the conversation was made while there was a third person present, the person can be a witness at trial. Unless the witness is impeached, the witness's statement may be sufficient for you to meet your burden of proof to show the statement was made, because the burden is just a preponderance of evidence in most civil cases. Note that, the existence of a statement is not sufficient to prove breach of privacy. The context surrounding the statement is important.
If you intend to record communications from the landlord in the future, please check with your jurisdiction's laws regarding recording of communications. Many jurisdictions (such as California) only permit a private communication to be recorded when all parties give consent. Not only an illegally recorded conversation is inadmissible as evidence (with the exception to rebut a witness), it is also a crime to do so. Some other jurisdictions in USA allows one party to record the conversation without obtaining consent from the other party.
No. Not just no, butt hell NO.
Telcos are not allowed to record calls unless they have a court order to so.
I. e. what you seek is impossible unless either of you is suspected of a listed offense (Katalogstraftat) and police obtained a court order to intercept that person's phone for that reason.
Even in that case, the phone company in question would not have a recording of your call but the recording would be with the police.
Although the list of listed offenses is quite extensive, I would consider it quite unlikely that you or your landlord is being investigated for a listed offense. That is, your proposal is a dead end.
The list of listed offenses can be found in § 100a StPO:
German: https://www.gesetze-im-internet.de/stpo/__100a.html
English: https://www.gesetze-im-internet.de/englisch_stpo/englisch_stpo.html#p0528
And for completeness, Art. 10 GG: https://www.gesetze-im-internet.de/englisch_gg/englisch_gg.html#p0058
The do keep metadata about who called whom and how long the calls were for billing purposes and, in some jurisdictions, because the law requires it for law enforcement. You can subpoena that. You usually have to pay the phone company’s reasonable costs in complying with the subpoena.
