I'm about to renew for about the third year, paying one year's fees up front (12 months for the price of 10).
I was with PlusNet before, but they whacked up the price, refused to treat me as well as a new customer,and the customer service was very slow and not very helpful.
I paid quite a bit more when switching to IDNet, but got FTTC instead of copper wire from the distant exchange, and the customer service is in another league. Very responsive, phone calls answered pretty quickly, emails replied to same day, Knowledgeable staff who know what they're doing.
Interestingly, they have not increased the price I pay at all since I joined, so they are becoming relatively more competitive on price than they were.