Smart (dumb) TVs - sudden loss of wi-fi connectivity on Samsung 7-series smart TV

UPDATE 13/4/2014: Problem solved. Thanks to Samsung and their local service partner, the problem was resolved by replacing a faulty wi-fi module (WIDT20R) at no cost despite being out of warranty. Balance has been restored to the universe.

I have a Samsung 7-series (UA55ES7100M) smart (dumb) TV. It has a nice big screen, good picture and is generally easy to use. I question most of the smart TV features, and have never used the 3D feature, but this is what came with a TV with a 55" form factor when I bought it. Since I got it unpacked, it's been hooked up to my home network wirelessly, initially over 2.4GHz then later 5GHz wi-fi after a router upgrade. Streaming of HD content was always smooth and problem free and Plex came along and made for a nice client through which to access this content. Recently though, the wi-fi connection has been decidedly flaky, and now doesn't really work at all despite no apparent changes in my home network setup.

Symptoms:

• No wi-fi connection from Samsung TV to any wi-fi access point I have
• Menu->Network->Network Settings allows wi-fi scan
• Not all access points show up to TV (all are set to broadcast SSID), despite them being visible to a multitude of smart phones, laptops and tablets from various manufacturers anywhere in the house, including near the TV in question
• Network Settings dialog box would bomb frequently after a scan for no apparent reason. Identified wi-fi SSIDs would be displayed for a fraction of a second then return to the TV display.

Attempted resolution paths (none of which worked...):

• Tried to set up multiple wi-fi access points (RS6300 at 2.4 and 5GHz, cable modem/ethernet/wi-fi router, Samsung Android AP). When these can be seen (not consistent), few, if any, successful connection attempts were made.
• Removed all authentication to see if that made a difference (it did not)
• Changed various radio settings in the access points, including forcing different versions of 802.11
• Tried to manually input IP address, DNS, gateway, netmask etc parameters in TV network settings but to no avail
• Did shut-down (via IR remote control) then power-down (at the wall) and restart of TV between network changes
• Released and renewed IP address on other devices on my home network to confirm the DHCP server was working correctly (it was)
• Reset both wireless routers
• Did full factory reset of TV. You won't find this in the manual, but for the model listed above you need to turn the TV off then press the following buttons on the IR remote control in quick succession: Info, Menu, Mute, Power. Note that the reset option under Menu->Support->reset doesn't touch network settings. The network set-up for wi-fi failed in the manner described previously, and for what it's worth, it took about 5-10mins to restore all the other TV settings from scratch via the setup wizard.
• I did NOT try to use a LAN cable (not really an option for me), but most people seem to report this generally works fine.

I appear to have v1040 of the TV firmware installed (via an online upgrade when the wi-fi set-up was working - strangely though, this version doesn't seem to be available on Samsung's website for download and installation via the USB method).

I have not yet tried to contact Samsung for support and can see that plenty of other people out there have experienced this issue, but none that have reliably fixed the problem (short of replacing wi-fi hardware module in the set itself).

The rest of my home network continues to work just fine and none of the access points have physically moved or been reconfigured or reflashed, and internet connectivity works fine for all connected devices.

Anyone out there had this issue and found a way to fix it?