Something similar happened to me at this property. I booked a twin room, but they only had kings left when I checked in. I said it was fine (despite the Diamond bed guarantee), but asked for a rollaway since I was travelling with a friend. The club and the front desk both said I would need to pay an extra T$1,200 if I wanted a rollaway.

I kicked up a big fuss since it clearly wasn't my fault. They eventually acceded, but it just left a very bad taste in my mouth, especially since this is Taipei where I don't expect such poor service. I've never been back and just stay at the W every time I'm in Taipei.