Anisa - leases don't come to an end on discharge of a legal charge. There has to be something else that causes the surrender for example a deed - see
Leases: determination (PG26) - GOV.UK (www.gov.uk) which explains the many ways a lease can be determined
So there's no other application form to complete and just AP1. You just need to ensure that you are applying against both title numbers and providing the supporting evidence to confirm that each transaction has happened.
For example - Discharge - form DS1
Surrender - Deed of Surrender
Transfer - form TR1
i'd suggest sticking to just the one contact channel as in my experience if you are using our forum and ringing the Qs will differ re content and therefore answers may vary or be unsure
And if you are unsure re how the lease has come to an end/been surrendered/determined then I would recommend seeking legal advice/assistance. There's a limit to the advice we can provide and we can't advise you on how your specific lease has been determined (surrendered) and what evidence you will need to provide to prove that