Let's consider, what exactly is wrong with it...
"It doesn't look very good", may not be enough objection to get it changed.
Housing assoc properties are not normally expected to be at the higher end of the aesthetic range. Their contractors are not highly paid for a "simple" job.
All works should of course comply with regulations, and hopefully normal working practices as well, but that gets grey.
He's used something like this
Or a longer one. Those are designed to seal on the inside of the soil pipe. That's probably working or your strategicaly placed kitchen roll would have become wet. McAlpine and Pancon hve good ranges
The gradient of the outlet can be 0° for a very short distance - Horizontal Outlet pans are like that now, whereas the formerly more available
P-trap pans were 14°.
There are
standard connectors avilable of various length to accommodate that from a HO pan.
Standard straight ones will accommodate a lesser angle, and you will find all manner of OK and dubious vari-angled connectors available. Flexibles have rough interiors - yuck - but have become acceptable.
Soil pipes should be at a minimum slope of 1:40 (Building Regs, Part H) which is only about 1.5°.
The problem then, is height. Poo is known by consensus, not to go uphill very well. That connector has to go downhill. It looks like it does,
just. OK he "should" have cut the soil pipe off nearer the wall, etc, but it probably works as far as the connector is concerned.. Loo pipes across the land are sub-optimal and accepted, so you're in that grey area.
If he had got the floor smooth and flat, he might not have had enough height. Again it looks bad, but is it "acceptable"?
The answer would be a definite NO if it's not stable
I think that's your complaint. "inadequate stability" will cause the pan to wobble and before long either become loose or
break the pan.
You could tell the HA manager, that it is likely to break the pan. You can invent a second opinion from an invented expert who says it will break or pull out. Then, ultimately, you can get a heavy visitor to come in and break the pan by rocking around on it. It'll crack out from the screw holes. or the screws will pull out
It's difficult to raise a pan. Wood is not suitable, one can argue. Because of its position, it would be insanitary.
A cement plinth would be more work than the proper solution of cutting off the plastic pipe.
You may have to measure carefully and make a drawing.
Diagrams are available freely on the net, you can paste them into Word or Powerpoint and adjust
That sort of thing, and show a wc-con7 or wc-con7b (link above) connector.
Neat straight extensions are available.
These are pan fixing screws. BUtthey would need new hols in the floor NEAR the existong ones, which could be a snag.
If you search for those you'll find posh ones with chrome caps for a few quid.
I would agree with the above - silicone the thing to the floor, using high quality sanitary anti fungal sealant.
Can't phrase it better than the poster above, that should give you something to go on..