the traffic offered increases if the GOS increases, that’s normal. Let me explain:
a cell with 3 TRX (21 TCH timeslots) :
at 2%GOS, traffic offered (or capacity) = 14 erlangs.
at BH, it means 2% of 14 erlangs are rejected and 98% carried.
at 50% GOS, capacity = 36 erlangs (i’m just imaginary value, ok ?)
it means at the BH, 50% of the 36 erlangs are rejected, and 50% are carried (18 erlangs).
The capacity is different than the actual traffic being carried, but you understand that the site, with this GoS, is designed to cover an area generating 36 erl at BH.