Please Help me!..Pep Boys said I needed a new Heater Core...believe it..they gave me an estimate for $750.00! The story...

After the engine smelling of hot anti-freeze,,thought i needed a new Thermastat...so thats when i went to Pep people to purchase a new one....they indicated that it was not the problem...duh duh duh...

I went home reworked the heater hoses (no heat anymore) and put a new thermastat in the car.....still heats up very quickly!

Water pump has no leaks...no noise from it....and the belt is not slipping!

Can anyone tell me the next step.....? ( someone did mention a bad head qasket) Car has only 112K miles!

Thanks Ed