Keyboard left arrow automatically repeating when pressed + degradation

Hi, 

after 2 years of use, my dell xps9370, intel i7 and touchscreen (the top 2 years ago) the more used letters of the keyboards are discoloured... this degradation due to simple use is a shame for such an expensive product.

Apart from this, recently when I press the left arrow in the keyboard, it cause an infinite repeating of left action, that can only stopped pressing the right arrow or Esc.

I have tried to uninstall and reinstall the keyboard drivers, but not any effect.

I suppose that the keyboard needs to be replaced, but before ordering a new keyboard I would like to know if some other causes would be possible (also because I wouldn't like to purchase another keyboard that is not able to resist to an intensive use no more than 2 years ).

Any suggestion?