Redemption rate change understanding question - Who has experience?

Hello, I have a question for clarification.
In the contract, an initial repayment rate of 2.78% is stated.
A maximum of two repayment rate changes up to 4% are allowed.
Now it is such that the repayment portion automatically increases over time and the interest portion decreases. This also increases this percentage to 2.78%+X and after a few years, the repayment rate reaches 4%, so that I can no longer use the repayment rate change, or am I misunderstanding this?

The decisive factor is the combination of initial repayment and interest for the monthly installment. If you then want a repayment rate of 4%, the monthly installment is basically increased accordingly as the initial repayment/interest ratio would have resulted with 4%. The actual ratio of interest to repayment at that time is not relevant.

so that I can no longer use the repayment rate change at all or am I misunderstanding that?

Sort of... maybe not for an increase, but for a reduction. The bank might even be happy about it because the interest income rises.

The decisive factor for the monthly rate is the combination of initial repayment and interest.

Are you sure that every bank supports this (admittedly very consumer-friendly) interpretation? To be honest, I'm not so sure about that.

ALSO special repayments are always based on the original loan. Repayment rate changes usually are too. Just take a look at the contracts or call the bank.

I have done it... had 2 free repayment rate changes included:

Letter to the bank:
"Dear Sir or Madam,
please change the rate for the annuity loan no.: xxxxx from 01.07.2018 to 4% repayment plus saved interest. The monthly rate changes to x.xxxx,xx €
Best regards"
And when calculating the rate, do not forget the interest.

The change in the repayment rate is always to be considered on the original debt, accordingly the installment to be paid in the future can be determined, and of course the interest portion is always to be calculated on the actual debt, accordingly the repayment portion in the installment increases significantly through the change in the repayment rate (if it is an increase).