Some industries get a bad reputation; telecoms, including ISPs, is one of them.
For almost five years we got our broadband from Zen. They aren't the cheapest out there, but they provided us with a solid service that I can only recall flickering once or twice in all that time. When necessary, their staff were helpful and pleasant.
When fibre hit our area we ended up moving away from Zen (BT seem to offer the best balance of cost and features on the service). I expected to be paying an extra month's charges for the 30 day notice period on our contract. Instead, they sent me a statement saying I was £16 in credit with them. Today I received another letter, asking for bank details so that they could send the £16.
I suppose it shouldn't be remarkable that a company is offering to refund a customer money that they overpaid, but it is. So, well done to Zen.