This was the whole issue though. I closed my bank account and moved country, and they delayed cancelling it and then chased me up on one month's payments for ye

This was the whole issue though. I closed my bank account and moved country, and they delayed cancelling it and then chased me up on one month's payments for years - when I had no easy way of making payments in Germany. In the end I paid it though, it was only 20 euros!