Yeah, they're not the cheapest by a long stretch, but if your connection is something you NEED rather than something you just LIKE... Andrews and Arnold are worth the premium.
If you will be losing productivity if there's any outage, you'll probably save the price difference the first time you use their support.
I've had good experiences with Zen too, on their FTTP product. (I'd have used AA, but they didn't offer that specific setup.)
+1 for Zen - they really know what they are doing. Unfortunately FTTC still requires intervention from Openreach who are still terrible.
I find Zen is a good middle ground between a reliable ISP with good features (like static addresses, IPv6, etc) and good support, and a provider like Andrews * Arnold who are excellent but will cost 2-3x the price. A&A are just not really suited to home use, and price a lot on bandwidth, which in the age of Netflix isn't great.
They have technical people running support who talk to customers as peers. Also you can use IRC if you don't like the phone.