How can I implement ticketing, SLAs, and KPIs in a company with a resistant IT team?

Hello everyone, I'm working in a company of about 70 end users, with our IT team made up of six members: a support specialist (that's me), a webmaster, a programmer, a DBA, a general coordinator, and a head of IT. Most of them have been with the company for over 15 years and are over 45 years old, while I've only been here for two years. I've noticed that there's no formal IT management process in place; all requests and issues come in via WhatsApp, personal emails, calls, or in person. There's no ticketing system, no prioritization, no SLAs measured, and no stats or satisfaction surveys. Everyone just addresses issues whenever they feel like it. If someone goes on vacation, users continue to message them on their personal devices, and if they don't respond, the issue just stalls. I've tried to propose implementing GLPI since my previous jobs used ticketing systems to measure SLAs, generate KPIs, and have clear statistics, but there's a lot of resistance to the idea of being monitored or controlled. Some examples of the chaos include last-minute Zoom room requests, incidences reported to personal emails, and the administration asking for KPIs that are impossible to gather without a structured system. Initially, when I joined, there was no documentation, shared passwords without control, pirated software, and multiple PCs activated with the same Windows license. I managed to implement some changes like migrating to branded PCs with Windows OEM, adopting Microsoft 365, and improving the network. However, I'm still seen as just support. Ironically, when I'm out of the office, both users and colleagues often call me because critical tasks depend on me, highlighting our lack of documentation. I plan to discuss this with administration, as they've started inviting me to meetings due to sensing the disengagement of my colleagues. They want KPIs, statistics, and SLAs, but the current management style makes this impossible. What structural changes would you suggest I propose to the administration to order the IT department, establish formal processes, and reduce reliance on specific individuals?