Just as an aside.
You should never let your van be towed.
Automatic transmissions can be harmed by towing.
You should use a dolley at least, and preferably a flat bed truck.
This applies to all automatics, not just Alphies.
It is not unusual to have battery issues.
Batteries can be tested by any competent garage, or Halford, Kwik Fit, and others.
They need to be tested under heavy load.
A voltmeter is not enough, unless you have a dead cell. (10.8v).
You must keep yours fully charged, certainly the starter battery.
If you park off road, a smart charger is a great investment.
Check for loose connections on the battery and earth leads.
Ensure the room (mood) lights are off, which can be difficult to detect in daylight.
I have dimmable lights running off the leisure battery; again essential to ensure they are off !