Tier 2 general extension - wrong Cos date by employer - advise needed

[ksivanandam]

Hi,
I need an advise on the below issue please.
I am on Tier 2 general visa
Current start date : 16/08/2016
Current end date ; 14/08/2019

I have requested my employer for Cos extension and they have issued th Cos yesterday. I was shocked to see that the HR has made mistake and started the
New work start date as : 17/08/2019

So it means I will be here in the UK without any visa for 2 days. This is causing me huge confusion.

1. First of all will this impact my extension application / ILR
2. Is there a way my employer can change the date to 14/08/2019
3. I heard about the SMS notes by employer option will the case officer consider this in general ?
4. What are the other possible ways to avoid any issues?

Please advise