No Debit order instruction for earlier date

I Have a Debit order for the date of the 1st of every month, for some reason the accounts people at Iemas have decided to debit my account earlier than stipulated, the debit order did not clear as to no funds in my account, i brought this to there attention and the answer given as February is a short month, this is absolutely *******, all my other account are on the first and they debit the following day they will debit my account if it falls on a weekend, not before the time at there discretion.