I'm sorry to hear of the challenges you're having. I've had zero tension issues and am just finishing up a large twin quilt top using 50wt Aurifil (top and bobbin) with excellent results. I thread through the 1st and 3rd thread guide/holes (always) and usually piece at 2.2-2.6 stitch length with tension just over 1.0 and get beautiful results. I'm partial to microtex 80/12 for piecing and 90/14 for FMQ - not sure if that's the correct needles to use but it's what's worked for me so far.
I hope she's not a lemon and that you'll find the sweet spot that works for you because truly the 2200QVP mini has been a sweet machine for me.
Good luck! Christine