I used to work at a telco and 2 of us supported about 100 users. It got WAY out of hand because they would just call us or email us if they had a problem. There was no way to prioritize the work that had to be done. If you got a call in the morning on a problem that would take most of the day, and then got calls for things that were minor (in terms of TTR), a lot of time was wasted.
I now do basically the same thing at another company and we use a ticketing system. We rarely, if ever, run into those problems. Even if we did, we'd have more time to deal with it, because everyone MUST put in a ticket when they have an issue. If you aren't using a system like this now it will require that you talk to some higher-ups about getting a system implemented and there will be policy change at the company, but the people that you are pushing the idea to should immediately see the benefits.