bungie
I replace two to three a month.
First let your household insurance know, as the investigation, location, and repairs of damage created in the fixing of the LEAK are covered. The repair to the pipe is out of your pocket.
Dont have just the leak welded over, replace the whole shower combination. Fixing just one point is futile as the break down of the brass is in the whole pipe.
Most times the work is done from in the shower tray, hence you need to get new tiles. You will not be able to match them 
DISCLAIMER
All advice is given with-out seeing the job, and hence all advice MUST be taken as advice with limited knowledge on the exact situation. NO responsibility can or will be taken. And yes, I am a licensed Plumber and Drainer with my own business in Brisbane Australia
