Uptime is not easy
Hosting companies have a lot to worry about : server stability, virtual server management, complicated administration rights, I get it.
But there is no reason on Earth that I can accept a hosting company falling to malware. Your staff is supposed to be alert to that, phishing is a well-known concept that network administrators are supposed to know by heart. A hosting company falling to malware has failed its number one obligation : having trained personnel to deal with issues. If A2 has indeed had its servers taken over by malware, then it is through sheer incompetence, either of management or in implementing procedures properly.
If I were being hosted by them, I would be transferring my site elsewhere pronto.