AF,
The problem at the boarding gate for regional flights is that you have 1 or 2 VK staff members and about 6 ALML staff members there. The VK staff members have on Vk uniforms with the name tags and ID cards very visible on them. They do not handle cash, and most likely will have sent your wife back to the check in counter.
If you wife was ripped off, then we might have to look in the direction of ALML or other airport staff, who should never have made any contact with her regarding ticketing and all sort issues.
My advice is do what has been recommended here and also contact the duty manager who was on duty on that day. They can tell you which staff members were assigned to that particular flight.
Let me add, VK does not treat acts bothering on corruption kindly.
Cheers