my payment is lost because i forgot to write the reference number

So I paid an amount of 75 euro that was showing outstanding amount on my o2 so I paid it on 15th of September but without a reference number directly to the o2 account usually its deducted automatically but since i had low balance it was credited back but I paid an amount of 75 euro in that day I already spoke with the customer service they tried to tell me to ask the Finance department but the problem was when I did try to talk the support person was not able to hear me. I've made multiple payments without the reference other seems to work but I don't understand how that 75 euro doesn't seems to please help me with the payment because of my o2 account it doesn't update my payment and then I get a monthly added payment together thats why my 75 euros is stuck somewhere 

(Rohan khatri (XXXXXXX DATUM 13.09.2025, 15.06 UHR ) this is the reference on my payment since I paid directly to the o2 account this was the reference but for other payments it worked but not this one

o2_Giulia, 24.10.2025, 15:02: persönliche Daten verborgen