Sponsorship license and switching from tier4 to tier2

[Riajacobs]

Hi, recently my employer had applied for his sponsorship license and been rejected. And he reapplied right after with a bit more details and answers to HO doubts and queries. because my visa runs out on the 28th this month, I'm panicking now actually. We haven't heard anything back from the HO and not sure what are the stages as well. I was just wondering if I need to leave the country right after 28/1?

Assuming my employer receive CoS by next week or so can I still switch it from tier 4 after my visa runs out on the 28th?

Do anyone know how long will it takes for HO to reply for reapplication? Because I heard they normally will visits for the second time.

Thank you so much will appreciate input and suggestions:)