Doesn't surprise me. I use them for landline indirect service (that is to say, the account still exists but is rarely used). Paying them is impossible. They don't take payment in the shops (a sealed envelope marked "billing" left on the counter followed by a hasty retreat is invarably lost), a cheque in the post takes weeks, and over the phone, although theoretically possible, involves so many transfers and instructions to ring a different (chargeable) number it's rediculous. Once they charged ny credit card without permission (and for an amount that bore no relation to the amount owing) and I got it reversed by the card company. My last payment was left with the shop and I'm not going to do it again, it's up to them to sort out. Never any communication from them.
I was at one looking at them for landline, but never in a million years!