As a data point for churners ...
7 months ago, a bank clerk made multiple credit checks on multiple days for the same credit card application. He made mistakes.

We filed complaints: to him, his branch supervisor, various ombudsman levels all the way to the OBSI. All confirmed in writing the mistake of the bank clerk, and at the same time saying they could not remove the wrong credit checks as they were not system errors but human errors.

At the time, they cost us 22 points - we could document because nothing else changed on our files during that time.

Today, 7 months later, the wrong checks (2) were finally removed. Score bumped up 10 points.

Seems hard checks do drag scores down for longer then 6 months... Something for churners to keep in mind.