You could park for free at Big C Extra on Klang, then a baht bus down Klang to SB then another along SB to the hospital (I am presuming Pattaya City hospital is where you are going).
Do in reverse going back.
How do you know they are illegal? They could be from Ukraine, Syria, Afghanistan or plenty other war-torn places. You should be proud they want to come to Great Britain. So much better than all those EU countries we left behind.