You bought 1 car from them 6 years ago. The GM won't even bother having his secretary reply to you. Sales cares about your money first and your happiness second. and you havent spent money there recently.
Don't consult with an attorney until you do exactly what i said. here. let me repeat
before you waste your time with a lawyer you need to find out what makes a car considered "CPO" from that brand of dealer you bought it from.
Most companies have stipulations on number of keys, mileage, and overall condition. If the repair was finished properly and the car had low mileage, etc... It may still qualify for CPO if they have no rules on accidents