Citibank — illegal use of credit card

Website:

Netflix.com &Netflix.com.final

Someone is trying to use my credit card for online transaction several times for netflix illegally. Hopefully most of the time it is failed but not sure actually. First it was netflix.com then again it was netflix. Con. Final. I didn't use this credit card still now. Moreover i didn't show the card to anyone. Neither i shared my own details of cvv, card number to anyone. I don't know how it can be used then also. Please do the needful as early as possible. I have been trying for so long to calm the customer care but all the lines are busy.