Three 4G broadband slowdown

Well after a couple of months of fairly good 4G broadband from three starting to slow down quite abit.

With my AI cube i was regularly getting 90-100mb (all be it i had to daily force 800/1800 bands with an app to get CA to work)

Now even when i force CA getting 50-60mb at most . Live in a village, Ibstock where most of it has either VM or annoyingly FTTP.

I have nither and only get around 25mb via FTTC. I did get a quote from cerberus but desktop quote came back at £6,800+VAT which is abit steep. Annoying houses only a couple hundred yards away have FTTP but no matter how much i bug BT they say there is no plans to add it to my house (although the BT fiber checker says different!)