Request $25 Deposit refund be credited to current bill cycle.

I returned the modem I was renting and was told the $25 deposit would be returned as a credit for next months bill. If possible, I'd like for the credit to be applied to this months bill cycle, which is due December 23. This isn't a priority or necessity, hence asking the form and not live chat. I'll probably call if I don't get help here by the 22.