Dear Pam,
there is a big bus (quite comfortable compared to all the minivans)
with the No 23 (I believe) starting at Patan Dhoka (there is a big bus
park), leaving basically all 10min and goes right through town up to
the police headquarters in Tangal, that's about 3min walk to the old
Bhatbateni Supermarket.
On the way back though, the bus goes into the bus park (Ratna park)
and you can switch to the next leaving bus or stay in the bus and wait
for 10-20min until your bus proceeds.
At least that's how it worked about 1 year back!
Hope that helps,
cheers
Julia