Telephone sanitization is easy.
Keyboard cleaning - not sanitization.
Cleaning the back of the tower... well never heard of that,
We are computer cleaning specialists and you cant just clean a PC. You anti-static vacuum cleaners. Otherwise you damage the chips inside. You also need to ware an antistatic strap,,, thats the minimum.
the vacuums are around the £450.00 mark.
Price is based on your time and is not part of a standard office clean except telephone sanitisation.
Dave
Hope it helps