http://www.fixmyradio.co.uk/ do warrenty work so if u have proof of when u bought it they will get it sorted for free if u got it under 12months ago, plus they send some one to pick it up and drop it back of and there pritty fast
You can repair speakers/ subs etc , well it depends if your speaker is High Quality !
If my sub ever breaks , it comes off piece by piece ! (Resonant Engineering) previously known as Adire Audio
Normally most speakers are serviceable
e.g spiders, voice coil, tinsel wires, cones , magnet etc comes off piece by piece and can be replaced or upgraded!!
It depends if it will be worth doing this to the average value speaker!