I also would like to recommend Dave from 'Down the Drain' - He came out within an hour (on a Saturday without any call out charge) inspected our blocked drained and advised that as we have a shared drain, that the blockage was Thames Water's responsibility. I wasn't aware before this that shared drains were TW's responsibility and that work can be carried out by them for free. Highly recommended for promptness and honesty (and friendliness!)