I think they are 7% fat, so they aren't free as they would need to be 5% or less, buthey aren't as bad as lean mince, which is usually 10% fat - so they are somewhere in between - just to confuse things nicely. Lean mince is 0.5 syns per 28g. You are unlikey to have ate more than 250grams which would be less than 5 syns if it was lean mince.
I've put the nutrition through the syns calculator and the burgers come out free - don't know about meatballs though. What a result!!
Based on this nutritional information Calories in Asda Leaner Cuts Beef Burger - Calories and Nutrition Facts
Admittedly, I guessed!!
This link to their site does say that each burger is 5% though which still makes it free - I just really want a burger!!!
ASDA Magazine - What’s new in store January