Wow... 4k only in 1 year...? Car for market run...? 

Anyway, recommended alignment balancing rotation is at 10k km interval at average, so it's not surprise for them to ask as per servicing SOP since 3rd service is supposedly for 20k km mileage - you should be on 2nd alignment balancing rotation already...

Since yours just 4k, can skip and do outside once it reaches 10k km... or when you service your car in the future when it can coincide with 10k km, say maybe on your 5th service...?

75 a bit steep for SC, the last I did mine at SC was 65...? Outside can do for less than 50 I believe...
BTW, if your car happens to be a V-spec and comes with Toyol tyres, may I suggest changing all 4 tyres instead of considering alignment balancing... Toyol tyres are death traps on wet conditions - a disaster waiting to happen...