Getting Sofas upstairs

[PiKe]

We were given a sofa which we found was impossible to get up our stairs, we were unable to manoeuvre it around the first corner and it got wedged between the walls.

Is there a particular make or brand that features a modular design in order to easily get it up stairs?

And before anyone says pivoting was not an option

 

[PiKe]

Just had a feel around down the side of the one we couldn't get up but the backrest is joined onto the arms and the fabric is stapled up underneath.

I can't feel any bolts that would facilitate removing either the arms or back rest from this particular sofa.