"....fresh fluid and a new filter is often all that is required to correct it. How do we know varnish deposits are the cause of gasman's problems, ayway (sic)?"

All of your objections have been answered in the other threads on this subject.. but it looks like you are too upset to go read them... so I will point out a couple of the most obvious answers... to whit :

We don't know he has a varnish problem... but many of us have used the trans-X on these types of problems and it immediately cured them.

The cost of doing this is WAY LESS than any other plan of action I know of and it does not preclude doing the OTHER things which cost more. It is a low cost attempt to logically correct what many who have taken apart automatic trans valve bodies know can cause problems.

If you have these symptoms putting only new fluid into the system does not introduce anything which would be expected to erase the build up of varnish by the old fluid.. thus the need for dissolvers.

Check the amount of fluid your transmission has.. it may take two bottles ( particularly since it comes in different sizes ) to follow the instructions with regards to strength.