HIfi-remote.com has an upgrade file for the Eltax HT-154. It uses the NEC1 IR protocol, device 0.191.
You're in the UK, right? Then a OneForAll URC-7950
has a setup code that you can customize to work, assuming the 153 responds to the same IR signals as the 154. The URC-7940, 7960, 7525, 7780, 7781, or 8350 would also work. OneForAll may also have some newer models that will work.
The remote will need customization, which you would do by entering a 5 digit EFC for each function. If you decide to go this route, we can tell you the 5 digit numbers.