Sorry Roy but my repair is still good after 12 months an around 15,000 miles.
Great, I'm glad for you that it has worked. However, your original fault was obviously not the normal master cylinder fault. As you say George, the slave cylinder was 'soggy' and appeared to have air in that section. Two things come from that 1) how did the air get in, and 2) if it got in once it can do it again, so it may happen again.
If Sparky's problem is with the master cylinder, as is the usual fault, doing what you did will not cure it, which is why I issued the warning. Also not all people are as competent at DIY repairs as you obviously are, and can end up making things worse. I've seen the results so many times in my job, and it ends up costing them more in the long run.
When it is your own car and it is you footing the bill you do find ways of repairing insted of just fitting new parts, as fitters do.
A fitter is just that - he fits things he is told to. He does not diagnose anything, he follows orders.
A mechanic is expected to diagnose mechanical problems as well as putting them right.
A technician is someone who can diagnose both mechanical and electrical problems and put them right.
I point these things out because people often use the wrong terminology. If anyone employs a fitter (who is the lowest paid) and expects them to diagnose problems and put things right, they will end up with problems as they are neither trained for that or possibly competent enough to do it. Sometimes garages do this which is one reason the customer does not get the work he expects, and I give no excuses for that. It is one reason I have always said we should have more control and people only allowed to do the work if they have certificates to prove they are competent.
Mechanics fit new parts for two main reasons - labour costs usually are so high relative to fitting new parts that the customers would end up paying more if they tried to repair things like this, so the customer is given the cheaper option. Second, since the manufacturer does not approve or often supply repair kits, tools, or give any information how to carry out a repair, their instructions are only to replace items, and if the garage is a manufacturer owned or licensed dealer he is not allowed to do otherwise.
The problem here is legislation and/or legal liability, especially now with so much litigation.
And finally, since you cannot tell how long a repair might last, and the garage would be liable for doing it all again at no cost to the customer, if it failed within maybe a year, the garage will not take that chance. The second time it might require additional parts because the 'temporary' repair simply delayed the point of total failure - so the garage now becomes liable for more than the original problem... No-one is going to take that chance.
So whilst I understand your point, if you do the repair yourself and it works, great, but if it failed again soon afterwards you simply accept it, whilst a business has to look at it in a different light, and you cannot blame a mechanic for a policy out of his control.
Roy