On danger of being tedious, [closed]

I'm not entirely sure if this expression exists:

On danger of being tedious, we are still waiting for the update that you promised many times.

... where being tedious could be replaced with e.g. repeating myself or being annoying.

If not, how would I express that I am (politely) sorry for the repetition in asking, but I need and rightfully expect something to be done?

Try "at the risk of being tedious"

at the risk of (doing something) idiom

: despite the possibility of (doing something that could be considered improper, wrong, etc.)
//At the risk of sounding rude, I have to ask you how old you are.

https://www.merriam-webster.com/dictionary/at%20the%20risk%20of%20(doing%20something)

Like Merriam-Webster suggests, it may be more common to phrase your sentence as: "At the risk of being tedious, I have to mention that we are still waiting for the update that you promised many times." But really, it's a common enough phrase that you could leave out the "I have to mention" and still be easily understood.

The first thing that popped into my head was a Paul Simon lyric:

But I'll repeat myself, at the risk of being rude
There must be 50 ways to leave your lover