I do too. But theres no real reason that the transition you are talking about, testing, ordering, fitting, any adjustments needed should have taken more than 2 weeks from initial request by you to delivery and use. Its not that complicated. When I ordered the last two chairs, I filled in the prescription form for the Invacare storm 4 myself. And had the area rep from the other manufacturer turn up and help fill in the prescription form, here at my property. In both cases the chairs were ordered same day, delivered in 2 and 3 weeks respectively.
(unlike you, I bought outright cheap, no details or service included, so I adjusted stuff like seating depth, seat position, CG, width, arm position, control pod placement, cables, and a few non stock mods myself over a couple of days. But that included some cutting and fitting non stock wheels, and making up new mountings for an actuator to get more recline, and reposition the control pod and rebuild the crap swing away etc. So not so simple. Still, 3 days, about 5 hours in actual time. Basic setup as you require, would have been 1 to 2 hours max.My chairs arrived like this: On a pallet, in my driveway, in a box! With no backs, arms, etc fitted. Then dragged into the house. Note the ridiculous position of the joystick!
Now since it took them about 7 or 8 months to delivery, how long will it take them to get it adjusted and fine tuned, eg joystick to not wobble, and be in the right place, and seating configured to how YOU want it after a week or two of testing, same with footplate, and programming, and to fix all the small details. The ones that they will forget like running cables, and stuff neatly and a few cable ties, or headrest tightening up, cutting off the sticky out bits of seating and headrest or push handles you dont like hitting everything. etc.
Ideally you need a fine tuning list of stuff you notice in the first few days/week. And they should then return and deal with it all in a day. These small things matter as they take a chair thats never quite right and turn it into something useful that you enjoy using. What are the actual chances of this happening at all? Probably zero. Or maybe in 6 months...
So its likely time for you to take charge and finish their job for them after delivery in jan? It may mean finding a volunteer with some basic tools, and a programmer. That has the confidence to take a hacksaw to various parts!
First thing I did was to bin the footplate mounting, the swing away, the arm mounting top brackets, the headrest mounting "scaffolding" and the 4 crap tyres. And the rear wheels, and a few minor bits like cutting off the push handles among a few other things... Then out came the drill and the saw! You probably wont need to do that.