Range Rover L322: BeCM after Servicing, any link?

Dear all, I had my 2010 TDV8 serviced with a full inspection 2 carried out that showed everything is running perfectly. I had no problems with the car whatsoever for over 3years I owned it.

Straight after I took back the car from service, I notice battery draining if I leave the car for 2-3days not used. All checks showed battery/alternator and different modules are fine.. but something doesn’t go to sleep mode and keeps draining power.
I am being told now that the BeCM unit has to be replaced as a last resort? Anyone had this issue before? Can Service damage BeCM or lead something to damage it? Any link? I don’t understand why it would happen immediately after service when there was no signs whatsoever before of any battery drainage or any electrical fault.
Can I do diagnostic reports to find out why this has happened ?

Unlikely to be BCM. Headlamp wipers (if fitted) not parking can drain the battery as can a fault with the heater fan speed control resistor. Water ingress can also cause problems.
Dealers tend to just keep changing things in the hope of eventually finding the problem.
Others who know more about the L322 will be along soon I expect.