Frustrated

Hi have been checking my statement and see that my credit card has been overcharged. This has been happening for awhile and I only noticed it now. I called 3 times and was told that I will get a call back in 1 business day. No call back after a week. Call again today. Today I asked why no call the back, the said she will help me and after a good couple of minutes I asked her to call me back and she's says they a no capacity to call back.