An update for my repeating keystrokes issue as mentioned above:
I have plugged the keyboard into the PC directly (it was plugged in through a powered USB hub before) and so far it looks like that may have fixed the problem.
It's a bit early to tell (since the repeating keystrokes didn't start happening straight away when I bought it), but it may just have fixed the issue.
For any of you having the same problem, please try and connect it to your PC directly, preferably to the keyboard USB connector (the closest one to the round PS/2 connector found on many motherboards or the one furthest up from the floor, usually USB 2 connector or if for you it's a USB 3, the nearest to it USB 2 one) and see if that helps you.
I will update if the repeated keystrokes start happening again and will contact support as recommended by Josh if that happens. Funny I realized that the hub may be a problem when I was writing about the issue to customer support!