we've been using the Ultimaker 2+ on our campus for quite a while and we're generally very happy with its performance.
Recently, my boss ordered a bunch of new filament, but since he didn't know better (or forgot to double check) we accidentally ended up with a bunch of 1.75mm filaments.
Now, the purchase was made at the end of last year, so I highly doubt we have the option to return the unopened stuff as its mid March now.
That being said, I've been trying to solve this issue the past few weeks (or months ... I've kinda lost my sense of time during quarantine) by caref