I have been a unifi user for 5 years . at subang jaya
Never had disconnect issues . if fact no issues at all so far.

Any issues so easy to log a fault report . i would say within 10 mins max

if onsite assistance is needed they will assign a technician within 24 hours.
you can track the fault ticket on your unifi portal .
you can see that the ticket is assign a technician and his phone contact within 24 hours
You can call the tech to check what time he plan to arrive or reschedule the visit time if he is OK .

100 percent of time the tech will be at your home within 24 hours . (my experience so far on 3 tickets this year. ( change hypp box , change router, fiber eaten by rat )

Unifi have a good SOP for this fault reporting and escalation process.
but some times things do go wrong . lemon cases !
I have no issues with unifi except that they keep change their unifi plans and some users pay more on fees. maybe this is expected due to competition.

Now with the 100Mbps at 129 rm every one can change their plan or subscribe if coverage permits.

i see no reason for changing to Maxis even if cheaper by a few dollars.
Restoration service is more important criteria for me . my 2 cents view !