how long for incorrect missed payment to be removed from credit file?

[Curlyjazz]

Morning,

My bank have added an incorrect missed payment to my credit file. They have agreed that it needs to be removed and I have this in writing. It's currently showing as missed - how long should I expect to wait before it's no longer showing? It's my only missed payment so I am concerned about it's impact.

I'd say around thirty days as that's usually the reporting schedule

I'm really unhappy about it as we were supposed to be applying a mortgage this month but we now have to wait until it's disappeared