Problem with creating a character shop.

Hi, I am creating my first game in unity which contains a character shop. I want to implement a buy button to change the value of my coins but cant seem to do so. Help would be much appreciated.
My code which is attached to my button:-

{

public int SpentCoins = 10;
// Start is called before the first frame update
void Start()
{

}

// Update is called once per frame
void Update()
{

}

public void Buy1stCharacter()
{
PlayerPrefs.GetInt("TotalCoins");
PlayerPrefs.SetInt("TotalCoins", PlayerPrefs.GetInt("TotalCoins") - SpentCoins);
GetComponent<TotalCoinsDisplay>().TotalCoins.text = PlayerPrefs.GetInt("TotalCoins").ToString();
}