Sorry to hear. I didn't have that experinece; it's been pleasant for me (there was a billing snafu while they changed their plan structure but it was resolved with a support email) and their monitoring has been very reliable since I signed up a year ago. Their service also seems to be better (4 checks/locations vs Uptrend's 2.)

Anyway, tl;dr is I never had an issue that resulted in not getting alerted about something that I needed to be alerted about, which, above all else, is the point of their offering.