The thing here is that you have already started travel on your AGLOB34 fare and that any remaining value will be based on a deducting what a normal oneway fare is which , trust me, won't be very much left.

An AGLOB34 fare is different from an AONE5 fare. So effectively it shouldn't be a one to one exchange as they both have different fare rules. You should refer to the original issuing airline and ask them. They ultimately have the final say if your ticket can be upgraded to AONE5.