Glad you're still up, ksand!! Hope that the result is good this time.
I'm on night shift tonight. Though I'm online on my phone so not able to answer in lots of detail.
Yes at the time we were running late and the employer only said how much he makes a year.
We now got a updated one stating he's non salaried
Ah, that explains the refusal then.
They base the calculation on what the letter says - if it said he was salaried, then they would have used the salaried calculation, only using his lowest payslip... in which case you didn't qualify for the visa and unfortunately it wasn't UKVI's mistake, it was yours/your employer's.
What annual salary was listed on the employer letter?