Anyone know a good reputable television repairman ? Samsung telly keeps turning volume down by itself.
You say it's not under warranty, by how much? You can go down the 'Consumer Rights Act' was called sale of goods act if it's not that old. Under 6 years. If it's under 3 years and you got it from a reputable retailer, its worth considering. You'd expect one to last at least that long. Do a bit of googling on the model number and see if it's a common fault. Could just need a system update.
Is it the handset (remote control) buttons that have got a bit grubby and are sticking? Happened to me and cleaning handset solved it.
This may be connected to the on-set controls. If you only control it using the remote, you may want to take the back off and disconnect the connector/lead that is plugged into the set-mounted sockets. This is a different model, but it may be that the issue is the same: https://www.youtube.com/watch?v=NPF3YW90YLU
New telly's are muck cheap now days, but... I'm sure there's a company at the side of The Light Spot on Ponty Rd whose sign advertises them as Samsung TV repair specialists. Never used them myself, just park my car outside there on match days.
Have you tried updating the firmware? There may be a newer version on the Samsung site that fixes the problem. http://www.samsung.com/uk/support/
As long as you follow the instructions it should be fine to do by USB (i.e. don't turn your TV off when the firmware is updating).