Changing end date of the job in assigned COS

[chakings22]

Dear All,

My Tier 2 extension is due now. I came in 2015 in Tier 2 General. My employer(He) chose extension for 1 year by mistake. He paid Immigration Skills Charge of £1000. He said my SOC was not exempt from ISC though I told it applies to applicants applying after April 2017. I have three questions:

1)Can he add 'sponsorship note' that the end date of the job is two years from now?

2)Since he paid £1000 (1yr fee), can I use the same COS if he pays for the second year.

3)Can he pay ISC for the second year though the COS is assigned.