Ok I am only another customer If unhappy with the official responses you are getting on the telephone use the complaints review service and list all the confusing info.
But My understanding is no customer on an old pre 24th june will lose the unlimited but the fup is being enforced.
Complaints review service details can be found in many threads on here or on the o2 support pages search for complaints.
iPhone 11 Pro 256gb on unlimited data
iPad Pro 12.9” 2020 256gb refresh o2 family discount
Apple Watch series 4
My first mobile was in 1995 a CM-R111 from sony on Cellnet.
Wincanton South Somerset (Full 4g 3G 2g indoor coverage) Remember we are all customers here not customer services