Visa expired soon, need advice, pls !!

[Et1234]

My visa is expired on 24th Feb, which is 5 working days from today date. I am extending my tier 2 visa with my 4 dependents. I have a full time indefinite employment with my employer/ sponsor.
My sponsor called up UKVI and was informed that they basically were too busy and no case worker to be assigned for my case to allocating the CoS.
I am curious if anyone has any experience receiving their CoS on the dot of the date their visa expired?
For my case, I am applying online, is it considered in time application as long as i submit my application before midnight on 24th Feb?
Is it common for me to wait for so long since my sponsor has requested the CoS for more than a month ago?
Can anyone advise me what happened if UKVI has not given me the CoS on 24th, what happen to me and my family, and what can we do in such situation?
I also want some advice whether legally (labour law or any law) I can ask my sponsor to be responsible for any extra cost in the case that I have overstayed in Uk and had to apply another 5 years tier 2 visa to get ILR, which costs me more than this round of extension application?

Many thanks

Ed

[nisarmalik]

From how long u r been in uk.
When u and ur dependent entered in uk

[Et1234]

thanks, Nisarmalik. It has been sorted.