Unreliable online calculator

Before buying the 5 buckets pack consider that this is an online calculator and, in my experience, server is unreachable most of the times you need it.
It is rather annoying to get the "unable to reach symbolab computation servers" message after have payed for this app.
Of course unreachable server is only an excuse they are unable to solve your math questions: try writing just a simple limit that involves a few steps to be solved and you get a server error. Now try with something like sin(x)/x and voila, the server is back again!
I think Apple shouldnt let apps like this on their AppStore.

Luca.I____i about Symbolab: Math Problem Solver, v1.5.2