We have a downpipe from our roof gutter that goes under the front elevation of the house, then under the pavement to drain out into the gutter. A recent downpour had water flowing out of the top of the down pipe, suggesting a blockage. We called out a drain company and they couldn't shift the blockage. They said it is blocked under the pavement. We don't know if water is running out into the front elevation, but if it is we risk subsidence. As the block is under the pavement we need BCC to investigate.