VW Booisen service petrol killer

I took my car for service mileage 30000 After service the car use more petrol

Full tank I use to go 950 km on polo vivo trending 1.4

After service 507 km full tank is empty

Service advisor : lesego ndlovu she was the one who booked my car for service

Service manager

Micheal

I took the cup for the 3rd time, but no luck on my car I purchased 3 times petrol within a month, but b4 it was once a month

If any one up there who having the same issue as my own and who have been helped please drop message and help me