I feel your pain. My last place was the same, couldn't even stream 480p on youtube. Eventually (5 years) we rallied enough interest in the building to convince hyperoptic to come install their service. Was great to be able to enjoy the memes thread once again.
I found the problem with the place I've bought.
Now I know why the sellers couldn't stand it and are moving on.
The broadband is ADSL only and caps out around 12 Mb/s. No cable, no fibre.
Damn.