Budapest to Sofia via Romania - Buying tickets during trip

1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

they had sleeper as well.

but the MAV write the Sparnight is not for Double or Single available.

This are just the Supliment to an existing Ticket like CityStar:

Couchette cars    6-bed cabin    € 9.40
Four-bed cabin    € 14.00
sleeping car    3-bed cabin (Tourist)    € 18.20
2-bed cabin (Double)    € 27.30
1-bed cabin (Single) *    € 63.70

but the MAV write the Sparnight is not for Double or Single available.

You are right and indeed in some cases there is no spar for doubles/singles, however nobody forbids you to play small tricks - e.g. purchase two 54 euro spars (2/3) + buy only sleeper reservation for the third bed in the same compartment, it will be extra 18 euro, but you'll get your desired "double"