Is Passenger Focus the complaint option these days ? Not exactly holding my breath.
Good [that you're not holding your breath!]
If the service that's being provided is within the
SLC▸ specification, then you'll find it's very hard to get support from official channels. Remember that the specification is set by the Department for Transport who also fund Passenger Focus - so
PF▸ tend to be very good where a
TOC▸ is failing to meet the standard required, but not good if the standard required of them is inapprorpiate in the first place.
You may also want to be aware before you get involved is shouting "this isn't allowed under the SLC" that the SLC can be changed - often with [limited] consultation, but I have also known it to be changed when it was pointed out that a service didn't conform. A quick edit ... and the officlal SLC which said "a train must arrive between 08:00 and 08:30" suddenly read "a train must arrive between 07:30 and 08:30" ...
Sorry if you find this answer a bit depressing ... there really isn't any officlal complaint channel, with the real answer being "if you didn't agree what was in the Greater Western Franchise, you should have said so in June 2005 when it was being consulted upon". However, you'll notice that political and popularpressures have added extra services on some of the Cornish branches, extra stops at places like Severn Tunnel Junction, and a whole host of other things since. Most of those stop short of things that need extra trains, however (exceptions - the Sleeper was saved, and extras coming next May on the Severn Beach line) if your request is going to need even one extra carriage you'll have a very tough fight.