Zulu . Did you get your own ICB report?or did bank give it out verbally to you ?
If not ,
Send payment e6 favour of Irish Credit Bureau ltd, ICB House , Newstead, Clonskeagh Rd, Dublin 14 , along with their personal enquiry form. You can download it from them.
On receipt of your ICB report you will really see where the (non-payment) issue is.
As a good guide, your ICB is not impacted until one month is down.
Write (do not phone) to Ulster , explain your position and ask to have ICB amended.
If they do not do that you can ask ICB to note the issue.Keep notes/copies of any correspondance/phone calls.
Ulster put you through all that hassle over maybe 2 days? If it was standing order Ulster Bank to Ulster Bank ,then you paid exactly on time.
If your standing order was Another Bank to Ulster Bank , then it might take 2 days.
If you paid via Direct Debit , issue is with Ulster.
It is very important to have statements , facts etc lined up before you do anything.