Unauthorised charges on my credit card

RAIN is charging my credit card with unauthorised amounts. They have my card details because I have purchased pre-paid SIMS. The unauthorised charges are not related to the SIM purchases. In trying to reach them -emails are returned because the email box is full; logging support calls on their website remain unanswered; and trying to reach their call desk is impossible. These amounts being charged are high! Unacceptable.