How does SpeedTest reflect the ISP performance - if at all

Having moved fro MyRepublic to Orcon in October 2019, I transitioned from download speeds of mostly 900Mbps to 2-300mbps.

I've been working with Orcon for a month and whilst they say their side shows 900+, I have only once seen that sort of speed.

If I run SpeedTest to Stuff Fibre server I get around 900

Same with Uber (Whangarei)

Orcon just sticks at 2-300.

So my argrument is that I am paying for Gig Service but getting much less.

Their argument is that as I get 900 from Stuff and Uber, and that they have tested at 900, my 2-300 test to Orcon is irrelevant (I paraphrase - "ignore the numbers" was what was actually said)

So after finally getting grumpy they tell me if I want to leave I can do so with no penalty.

All I really want to know is

1. does the speed test I run reflect the service I am being provided?

2. would it have been fairer just to charge for the actual level of service?

They are saying options are

1. stay on GIG and suck it up

2. reduce to 100/20 (not sure if thats enough for uploading graphics and videography files)

3. go elsewhere (but be released from the early termination fee).

Any thoughts from fellow consumers out there?

Thanks

Mal