Just had exactly same problem about battery not holding it's charge. After much to-ing and fro-ing (that's another story!) eventually got the supplier to agree the battery is duff and replace it with a new one.
It's an Elecsol 110 a/h with a five year guarantee. In fairness nearly everybody is surprised that it's failed, which is probably why I've had the hassle.
By the way, mine discharges at 0.2 - 0.4 amps all the time too. Never been able to find out why, suspect it's the control panel itself, seems to be better if I switch the control panel off. Like the suggestion about the reversing camera - must check that one out.
Terry