What's a reasonable expectation of quality of service in this high-volume scenario?

I work at a co-working space where the management has a contract with a local IT company; I'm convinced that they have no idea what they're doing at this point.

For some context there's a public and a private wireless network in the same open 5000 sq ft space. Each network probably sees around 200-250 connected devices at peak usage for a total of 500 clients at peak usage on the same infrastructure. I imagine they have 5+ wireless access points (Cisco Meraki) to serve everything and at least one dedicated, business-class 1Gbps line.

A few weeks ago the entirety of the user base had major issues connecting such that some people had no internet for an entire day; these issues persisted for a week. Many of these issues have since been mediated, but the network is still randomly latent. The current situation is that most people will be fine with the internet browsing experience they get, but my quality of connection drives me up the wall purely because I use a lot of command-line utilities that are atrociously-sluggish at executing 100 different API requests when the network issues spike.

When I run ping tests against 9.9.9.9 I will sometimes get averages of 100ms with max's and min's of 750ms and 15ms; at times packet loss can be as high as 50% during the random spikes which do in all fairness happen less often now. Within a single 5-minute period I can get 140down/40up and shortly after 10down/20up in a speedtest.

I check my Linux syslogs to see if my Ubuntu 16.04 machine has been doing any switching between the various APs, and the answer is usually no. I've also seen scenarios where my laptop remains connected with good strength to the wireless network but has 99% packet loss for 19 mins and suddenly the network seems to self-correct. (Nothing occurs on my end as the syslogs would show AP or network switching).

Am I going crazy? I can see that most other people's internet access is not greatly affected by the shaky service, but I can't help but notice every single time that latency spikes or throughput decreases. What's the best way to demonstrate the issue to them? Perhaps the issue is with my laptop (it has a recent 802.11ac card from Intel and up-to-date drivers)? Is there even an issue? Are my expectations too high? Could it just be QoS between the public and private networks?