You might be experiencing what i would call "tower speed shaping".
It has happened to me:
I have logged a call with 8ta because in Nov last year i was getting the following stats:
Download Speed: 6.39 Mbps - 7+ Mbps
Upload Speed: 1.24 Mbps - 2.5 Mbps
Latency: 69 ms
currently i am getting between:
Download Speed: 0.35 Mb/s - 3.99 Mb/s
Upload Speed: 0.21 Mb/s - 1.29 Mb/s
Latency: 80 ms
Yesterday when the 8ta Rep came around to test at my house he told me that they can add / remove speed from the towers as need be. If for example there are 10 people connecting to a tower and they are getting speeds of for example 9 Mb/s and there are 20 people connecting to another tower and they are getting 2 Mb/s, they can decrease the speed on the one tower and allocate it to the other tower.
Then he has the nerve to tell me that my internet speed is fine and the tower is performing like it should.