UPDATE: I have been informed by Retrosix that they are now an online-only business (20th June 2024).
In terms of selling retro games, Retrosix only offer a tiny few retro games. However, they are a reseller of multicarts for various consoles.
Where Retrosix truly shines is in their expert repair of almost any console.
I have personally used their repair service at least five times, and each time it has been excellent.
Retrosix also produce power upgrades for older consoles including the Saturn, Dreamcast, and Sega Game Gear most notably.They are also known for their excellent screen upgrades for handheld consoles including Game Gear and Lynx.
You can find Retrosix at 9D Millrise Rd, Milton, Stoke-on-Trent ST2 7BN.