Samsung Smart LED TV endless problems and now urgency to resolve problem on a unit that is under warranty still.

Samsung South Africa a brand I have used for many years now and have a house full of Samsung products until now... I bought a 58'' Samsung Smart LED TV from Makro Germiston last year in August Model No UA58TU7000K which is still under warranty with Samsung. I had a problem about a month ago whereby the TV just switch On and Off the whole time. After a huge battle to just get someone to come and have a look at the TV I eventually got told this is a problem Samsung Globally has on this specific Model TV and that they will replace the TV under warranty as there is no replacement part for this problem on this TV. Then about an hour later a replacement part or upgrade part miraculously arrived in South Africa from overseas which they will use to repair the fault on my TV. I was not happy with this due to the fact that they said it is a replacement part after they had no part available in South Africa. I was also told that this was a common problem on this specific Model of Samsung and that they have it globally. I got pushed to the repair center to come and fit the replacement part which I was not very happy about but gave them the benefit of the doubt. They replaced the part a week later since the problem hit on the TV and the unit was fine for 2 weeks until I started noticing marks down my TV screen a Wednesday evening about 2 weeks ago. The Thursday morning I phoned Samsung and the repair company to advise them of the problem I have with the marks on the screen which I was asked to send them photos of which I did so immediately. Again no one came back to me. I had to AGAIN drive al the way to Makro to beg for assistance whereby a gentleman from Samsung assisted me to get the process done with some speed which also did not help at all. Eventually after I had to call again to ask for a response the repair center phoned me to come and have a look at the TV which they have done and now a further 4 days have gone since any feedback from them or Samsung. I had to call Samsung again this morning to ask for feedback and was told they waiting for feedback from the repair center but also spoke to them in the mean time and was advised that my TV has been wiped with a wet cloth and hence this is the reason for the marks. NOW let me tell you one thing Samsung I have had Samsung TV's all my life and have always used a very damp cloth to wipe my TV screens we have been doing this for years now and never ever had any issues. Why will this now all of a sudden happen after the TV unit was opened up for the replacement part to be replaced? How do I know if the units was secured properly? We have wiped the TV ever since we bought it with a very damp cloth every now and then and now after your recommended repair center arrived to replace the part I am sitting with the marks down my screens there is also a D3 symbol on the TV screen which you can easily see when you stand close to the TV. This was never on my screen before the part was replaced. I did point this out to the repair center technician and he said it is normal to have this mark on the TV. I highly doubt this and can honestly say I have never seen this D3 symbol on my screen before. I am very confused on what to belief anymore. I am so disappointed in this whole experience the past month and a bit and specially with a product like Samsung. I know after this post Samsung South Africa will reply and apologize for the inconvenience caused and that they will make contact with me but I seriously just want a TV that will work and last me at least a number of years like all my other Samsung TV's I bought before and own.