Every time the subject of Plusnet comes up, I feel obliged to retell my tale of woe, even though it's getting a bit out of date now...
When we moved to where we live now, nearly eight years ago, I signed us up to Plusnet because they were offering the best deal at the time. Unfortunately, it turned out we couldn't get broadband at the time.
After several months of trying unsuccessfully to get through to Plusnet customer services by phone, web contact form and email, I decided to cancel my direct debit to them. So they sent the debt collectors round. If I'd known then what I know now, I'd have refused to pay, but I did pay and I've still yet to get a refund from them. They owe me about £400.
To put the story in some context, this was at a time when Plusnet were going through rapid growth and clearly they didn't have the infrastructure to cope with the extra demand. I expect they've resolved that by now. And for most people who don't have the same bandwidth issues as me, this kind of problem is unlikely ever to occur anyway. But take it as a word of warning none the less: firms like Plusnet that offer cheap deals tend to make their savings in areas such as customer service. This means that when things do go wrong, it's often harder to get them sorted.
Which is not to say that paying more money to a firm like BT will necessarily get you better customer service, but you know, caveat emptor and all that.