Hi gnitin
The Swiss Travel Pass is only valid for the printed dates and all routes marked on this map. Your ticket is therefore not valid for 12 october.
An exchange (for a fee) is only possible under certain circumstances. I recommend you to enquire directly at a SBB railway station ticket counter or to call the RailService under +41 51 225 78 00.
If you didn't purchase your tickets with SBB, please refer to the issuing office directly.
Kind regards
SandraI