O.k then as I was saying this would be caused either by a defective Y-scan drive board or perhaps a bad connection on one of its connectors.
This board if it has to be replaced ,cost around 20 to 30 pounds and you can expect another 60 to 80 pounds to have this done at home .
So all in all perhaps 90 to 110/120 pounds .
Bit difficult for me to say what the repair shops in the UK charge for a service call these days.
If you`d like to find a Samsung ASC (authorized service center) near you , click on the link below and enter your postcode and the info about your tv ;
This will list the closest ones to you.
Wish i had better news and an easier solution for you today but i hope this help and I will be in standby if you have any questions.
Thank you and please take the time to rate my answer if that answers your question and you can still reach me here at anytime after this chat is closed if you have other questions.
Please note that from where i`m sitting there is just so much that i can do and if you are going to rate my answer below O.K service then please do not rate at all , just let me know.