recently noticed dampnedd on an external wall adjacent to a chimney. Got 3 estimates ranging from £125 for side flahings only +soakers, £140 for side flashimgsand soakers, . The third said £380 for side flashings, back apron, and cover flashing replaced. Not sure which to go with sinc ethey all say somthing different is causing the dampness on the wall. Does anyone have any good advice ?