vauxhall corsa water leak?

Hi all,I have same problem,2005 corsa 1.4SXI,(purchased new from vauxhall dealership)external water leak into drivers side footwell,definately getting worse,I have looked at fault finding & remedial works but as not mechanic cannot undertake it myself.I have been quoted £600 by vauxhall main dealer (to investigate & cure this problem)??.This leak problem seems to be a common & widespread fault,part of the vehicles build construction failing,as the source of the leak is inaccessible to the motorist regarding simple routine maintenance,vauxhall seem not to want to help,maybe a feature on watchdog or similar is necessary.