Well Per, you are correct that the LX2802 has a dual tuner covering
VHF 46 to 300 MHZ which in the UK was allocated to channels 1 to 13
UHF 470 to 855 MHZ which in the UK remains allocated to channels 21 to 68
So, the LX2802 cannot be upgraded to pick up the frequencies between 300 to 470 Mhz
In most of Europe these frequencies were/are allocated to transmissions other than TV. Clearly since the LX2802 a lot has happened with frequency allocation around Europe, and we have cable now as well and they can transmit on any frequncy they like really within the terms of any licence.
So, the bottomline is, your LX2802 is working correctly, but your cable company has decided to transmit on frequencies not previously used for Television in most countries.