Theft in Texas

My question is for the state of Texas.
I was discovered taking roughly $300 worth of merchandise from where I worked, when it was discovered I signed some papers stating what I took and payed the company back the $300 that very day, two weeks later I get a letter from palmer reifler and associates for a civil demand WHICH I payed the day I received the letter. Now here is my question I received another letter from palmer reifler and associates asking for the $300 for restitution for the store even though I have payed them already, also there where NO police involved during all of this, what should I do?

plz help

The first amount you paid was to reimburse the store for the items you stole.

The new amount is a "civil demand" - a statutorily authorized fine that allows the store to recover losses due to theft including an amount toward its theft-related overhead. Your paying for the items you stole doesn't help defray, for example, the cost of their loss-prevention efforts.

If you don't pay the civil demand, they can sue you. Given that you've apparently signed a confession, I personally would be concerned that your nonpayment might inspire them to belatedly report your theft to the police.

As I stated in my original post, I payed the civil demand, they are trying to get me to pay the $300 to the store, which as I stated I have already payed back the store.