Having watched his side surrender a 1-0 advantage, Vance was not a happy man on Saturday evening.
'Controlled the first half, terrible second half and deservedly got punished and very disappointed,' he said.
Ross Allen gave GFC a half-time lead, but also missed a first-half penalty, before Brotherton and Bosma both scored for Peavehaven & Telscombe after the interval.
Elsewhere, Folkestone Invicta, so impressive at The Lane the previous week, were held 1-1 at home by Dorking Wanderers and sit top on 10 points, one ahead of a group of five sides on nine – Hastings United, Chatham Town, Herne Bay, South Park and Faversham Town.
GFC, who play Hythe Town away tomorrow, are four points off the top.
More in Monday's Guernsey Press.
