undependable

US /ˌʌn.dɪˈpen.də.bəl/
UK /ˌʌn.dɪˈpen.də.bəl/
1.

ไม่น่าเชื่อถือ

not able to be trusted and not likely to do what you expect:

:
•
Electricity is so undependable that lights go out in the capital several times a day.