I hate to tell you this, but the only way to stop this charge is to cancel your credit card.
For years, and especially more so since about 2006, there has been a major surge in emailed spam for so-called 'Canadian Pharmacies'. According to reports, this has also caused significant harm to the legitimate pharmacies in Canada according to their industry associations.
Several gangs exist, primarily Yambo Financials, and a Russia-based gang that is headed by Leo Kuvayev and Alex Polyakov, and possibly other gangs. Leo Kuvayev was arrested in the United States and while awaiting trial on charges of selling prescription drugs online, made bail and upon release from jail, left the country and soon was sending large quantities of email spam for pharmaceuticals, largely prescription drugs.
One can tell these sites from legitimate pharmacies, due to domain naming techniques employed by the spammers. One gang uses domains with two words run together, such as prizechange, always followed by .com, and the other uses seemingly nonesense words, like qiyidevoh, always followed by .cn (domain extension for China). Most of the sites look very similar, although at times there are differences, or new versions of the pages appear.
Most of the offerings of the spam gang sites are for drugs like Viagra, Cialis, or opioid painkillers like Vicodin or Oxycontin. However for the most part the pills shipped are either very low strength, having been made from full-strength pills that were 'cut', or are nothing more than placebos with no actual drug content in them, thus adding to the damage, and the dangers, of purchasing from these sites.
These companies are attempting to get your personal and credit card information. Do not answer these emails. Do not place an order with them.