If someone has a long lease and a share of the freehold - a few years ago the other leaseholders got their leases extended along with this chap - but they didn't extend his separate lease of his garage - I don't know how it got overlooked - can he now insist his garage lease is broght into line and extended too to 999 years?
If the other leaseholders also had separate garage leases and those were extended then the one that was overlooked might have a reasonable case. Otherwise, I agree with bm.