interior

go under the car and see if you can find the hose drain for the heater/ac. then run a wire up it to see if it'splugged ornot. if not that check your heater core for leakage with a pressure test

i justed had the car in for a full service a week ago they said everything was ok,the car inside doesnt smell of antifreeze

Water gets in via the pollen filter, a common issue on these, I answered same question elsewhere on here, 2 minute job, no tools or parts required.