i have a vauxhall corsa club 12 v 2001 problem?

iv only had this for about 2 month and within that time i have had to fill the engine coolant on 2 occasions because it was bone dry, i had a look about and havent noticed any leaks so im not sure what was happening there. anyway shortly after filling it with engine coolant for the second time i started to have trouble trying to start it and the service light was on so i booked it into a local garage. they couldnt find any problems but gave it a look over and run some sealant through it to fix any leaks he might of missed and told me i was good to go. when i started my car the service light was no longer there but instead the malfunction light was on ( one that looks like a little engine) i drove it around for 20 minutes or so before getting home and it stayed on the whole way. once i got home i turned the car off left it for about an hour and tried to start the car and it just wouldnt start also the oil light started flashing. i called the garage back and they are going to come out and have another look at it. im just wondering if anyone knows what the problem is and is it a common fault with these cars?