What methods of support do you offer to your customers?
Just e-mail? Maybe IM or live chat?
As a support engineer, based of my experience, one of the known reasons that companies loosing their frustrated customers for their poor support strategies.
Even though SLA's are bounded with support systems, the customers always seeks a quick resolution on their issues, but in such situations help desk team can't always deliver immediate and a timely resolutions through emails only, because the tickets might be prioritized, for large volume of queues.
In that cases, the issue with less technical complexity and with high urgency can be resolved by the means of Live chat.
Apart from that, for larger companies with a multinational client base, should always have the phone supporting options to support non English speaker with their queries. A toll free based phone systems can reduce quite large ticket volumes for the sales as well as support department, but is an expensive option for small or mid sized companies as well.