No they don't at all.
Your connection runs as quick as your line can support.
The only reasons I left were:
1) Despite the exceptional efforts of the tech support guys and girls my long line meant BT's DLM was always whacking my speed down when I got to around 3.6 Meg, I've had a much more stable connection on the O2 Wholesale service through Xilo but of course your mileage may vary (my line has a downstream attenuation of 58 dB)
2) My usage was increasing to a point where I'd have had to keep buying additional usage or up my package to a level that personally I'm not really happy paying per month albeit Zen did double the allowances last year for no extra charge and BT does meter ADSL connections so this gives smaller ISPs less room to manoeuvre
Both my landlines remain with Zen as the price for these is excellent as is the support for all their services, (they quickly got Openreach to sort out a voice line fault for me),that is equally true of Xilo, in my experience.
In a nutshell I am happy to deal with both companies and am happy to say to you that I don't think you will be disappointed if you do go with Zen.
Virgin (ADSL) => Namesco => Newnet => O2 => Plusnet => Zen => Newnet => Zen => Freeola => Vivaciti (using O2 Wholesale DSL) => Xilo (C&W Wholesale) => Xilo (O2 Wholesale)
Router: Billion 7800N
Note: I don't lay turf for anyone. astro or otherwise, all views and opinions expressed are my own based on experience.
Edited by techguy (Fri 05-Apr-13 20:40:42)