Hi,
The digital Freeview service requires a really clean (low noise), high strength signal to work properly.
The 315 is an omni-directional aerial, which is designed to pick up signals from all around - so you don't need to align the aerial.
Your 315 omni-directional aerial will receive all the competing signals from other TV transmitters in the same region, plus any reflections from buildings or hills. And because the aerial is physically small, it doesn't capture a strong signal, so the integrated amplifier will boost all the signals it picks up (and adds it's own bit of electronic noise as well).
Freeview needs a strong signal with low noise, the output from the 315 has loads of noise and competing signals - not too much chance of success - as you discovered at home.
SOLUTIONS:
Upgrade the 315 to the Status 350 directional version, which needs to be aligned with the transmitter but does reduce competing reception from other directions. Not tried but it stands a chance of working.
Or buy a cheap roof type TV aerial and mount this on a pole - these work - but are very ugly.
And finally use the 315 aerial for a game of frisbee - probably quite good as a frisbee disk.
Robert