All merchant guild side quest problems were fixed by the official 1.33 patch for original CD release of the game:
- Merchants Guild Tingalf quest problem solved.
- Fixed:Becoming a member of the Merchants Guild by paying gold doesn't work.
- Fixed:Trevor dialog, can expose Tingalf before receiving quest.

GoG release of the game should be considered deprecated because it doesn't contain fixes added by official patches (and patches cannot be installed over GoG release due to incompatibility). Moreover GoG release have even more problems compared to official (unpatched) game release from 2002.