Incorrect billing amount

Good day

I have been waiting for a call from the billing department for WIFI provider RAIN,

I have and overdue balance with the, However it seems to be incorrect I have been waiting over a week now for someone to call me with feedback.

My account with RAIN was created in December 2024, which was about 7 months ago, my RAIN subscription is R649 Which amounts to R4543 which I understand.

RAIN however says that I must pay R4543 plus R1875 so I would like to know where does the R1875 come from?