As always--you should have security tools to protect your system, but avoiding phishing scams is part common sense and part cautious skepticism. Could your account be blocked due to suspicious activity? Absolutely. And, I would hope that a company like Global Payments would do just that--as quickly as possible--if, in fact, unusual account activity was detected.
However, in the event that such a thing actually occurs, a company like Global Payments will not ask you to click on a link in an e-mail and share or change your account credentials. Do not open file attachments or click on URLs in e-mail messages unless you are 110% sure you know what awaits you. If you are concerned that the phishing message might be legitimate, pick up the phone and call the customer service department to clarify.