Hello!

There are no bugs related to Drachmas' disappearance. The game is developed the way that the in-game currency can be spent only on in-game purchases. Please follow this article to learn where the Drachmas are commonly spent.

4 Vespasian said:

i did not spend them as i have stated already. The game was playing up and freezing. When i restarted the game the drachmas had gone. 

You know, the best thing about Drachma's use is that it's impossible without a corresponding command. So, most likely, you did spend them in the game.