Fibre connection drops - devices also drop

[#1]

New customer, and very unhappy with service so far.
Before we go too far, let's make it clear, i work in IT and am not naive with computers
However, when my devices drop from the router (there are at least 3 at any one time) and cannot even SEE the router, then i get annoyed.
When they are connected and the signal is poor when standing next to it AND i have 1 device connected by LAN that also drops - speed/stability is awful then i get pretty dam angry with the poor service.
I pay for 40mb fibre, which i get probably 50% of the time - when i am at WORK. Evenings is dropping 2-3 times and router goes INVISIBLE to my devices until i restart it.
Fed up with the bulls*** i get fed by support "oh your line is still calibrating, or a virus, or it's normal"
Normal? please don't patronize me....
I live close to town, on a fibre optic line, i expect 90% of the quoted speed, 95% of the time, with 99.99999999% up time - not this mickey mouse broadband rubbish, even TalkTalk is better than this.....and THAT is saying something.

[#2]

I'm guessing you are trying on wifi - have you tried a wired connection?
Have you checked the wifi channel you are using is not being interfered with by neighbors routers etc?

[#3]

He said that 1 device is connected via LAN and that also drops, so doesn't sound like a standalone wifi issue

[#4]

True, missed that.
But router going invisible, and poor signal strength IS all wifi.
Only explanation there is interference, or faulty router.

[#5]

@MrPip - what router are you using? If it is the new 'zero' router (the one that stands up on its edge), a lot of people have been complaining about it. I don't have any experience of it myself, but one thing you could try as an experiment is to make a PPPoE connection directly to the BT modem. This would take the router out the equation and let you see if problems still occur.
http://community.plus.net/library/broadband/fibre-help-how-to-set-up-a-pppoe-dialler-in-vistawindows...
The other thing you could do is try a different router (if you have one or can borrow one).
I am not saying the above are convenient options, but I think the first step is to establish if this is a router problem or not.