Latency spikes when browser opened on same or other device

[#1]

Hello there,
We have the unlimited package here over copper (No fiber in area). The connection speed is very stable and latency is great. I play League of Legends on PC with constant 35ms, which I am ever so thankful for. But...
Whenever I open browser, or someone else start to use the internet in the house my latency shoots up to 150 and gaming becomes impossible.
My download speed is coming at around the 11Mbps mark, however the upload is 0.3Mb.
I have a feeling that it has something to do with the limited bandwidth on the upload.
Is there anyway this could be fixed? Perhaps increase upload speed or somehow protect a portion of the bandwidth to my PC?
Thanks,

[#2]

Easiest way is to raise a ticket  here https://www.plus.net/wizard/?p=wizard&page=22883&wizard_id=38

[#3]

Hi there,
Just placed the order for you, it should uncap early tomorrow morning for you