under nc contract law is there a grace period for breaking a contract?

There is no grace period implied in North Carolina law across the board on contracts, but it may have been a standard feature in the Dish Network contract that you retained the right to cancel without penalty within a certain time period.

You should demand of the third party collection agent that they provide verification of the debt and copy of the contract. Request a copy of the contract from Dish Network as well. Even better, if you can get Dish Network to acknowledge in writing that you canceled within the contract's grace period and are not liable, you should be able to forward a copy to the collectors. You may even be able to get Dish to call them off for you.

If not, don't give in. Demand that they provide copies for you of the documentation that you agreed to this contract, the terms of the agreement, and any other evidence pertaining to the breach and the claimed debt. This is evidence they would have to produce if they wanted to successfully sue you for the debt. If they can't produce it, they're not likely to be very successful suing you. Many collectors don't care about having a provable claim, but simply want to harass and bully you into paying. If you don't owe, you shouldn't pay. If they do sue you, consider hiring an attorney.

Good luck.