2704n router not able to provide a Wi-FI connection of any use

[#1]

I have genuinely had enough. Putting aside the fact that I cannot get fibre optic, I'm stuck with 6megabit download speeds, my mobile internet is over 5 times faster and there's no hope of any upgrades;

My 2704n router cannot provide a Wi-Fi connection of any use. I have used a Wi-Fi analyser to look at the channel situation in my area and all channels are bad. 11 is the best and for a while after switching to it, the problem seems to be fixed but never is. My ping in my favourite games is unstable, 10 seconds doesn't pass without a ping spike of at least 100ms, with the highest normally being 300ms, but some spikes going to upwards of 3000ms making the game glitch. 

The router itself seems to not be up to the task of much at all, port forwarding does not work despite the rules being set by myself and them being exactly the same as the rules that worked on both my old routers. And even though it's not relevant I do find it funny that there's typo's in the software 

How do I fix the wifi problem?

Edit: I thought i should also include this:

Line speed has been checked, it's awful but it's ADSL so it's to be expected.

Noise and attenuation has been checked, all is fine. 

[#2]

@Thomas5020 - Looks like your only viable option is to use a wired connection. And 6mb isn't that bad to be honest.

That's enough to watch the likes of Youtube and BBC iPlayer without any problems.

[#3]

alternatively try a Powerline device

[#4]

I'm in a bit of a financial hole right now, and the powerline adapters I need cost £40 (need passthrough ones), so as it stands I can't get them. I would fix the problem though 

[#5]

6mb isn't bad provided that is all you do with your connection. But for me, I have to share 6mb with another 2 people who both stream and download. If somebody is downloading or streaming HD video, it's very noticeable for everybody else even if they are just trying to refresh their emails or use facebook.