I Would not be surprised if this was just the first answer they tend to give when they are not sure as to wether they should delete it or not.

Sadly, the way it tends to work in most of this companies is that they get so many requests that an actual lawyer cannot check them all, so they employ just normal people to check the requests over and decide on them, which then leads to mistakes unless escalation happens.

On that note, you need to escalate.

I would look at the GDPR (DSGVO in your case since DE) articles and base you request on them. For example: I request my data to be removed according to GDPR Art.17 since there is no longer a ground for my data to be processed / I am not a person of public interest / I withdraw my consent for my data to be processed.

It has worked for me in the past, you just need to get passed the first barrier which is mostly just a normal person replying with some canned answer.

Best of luck!