5G finished in one day? impossible where did my data go?

hi

I have a contract of a wifi router with Telkom of 15G,5G day and 10G night. On 2 December i tried to connect but could not then when i check my balance it stated my data is finished but i could not even connect. Where did my data go? I called and was advised i used it up on 2 Dec but that is the day i switched the router on and could not connect. month end i will have to pay for data i did not even use this is just unfair i want my data or elsedo not charge me. I want an explanation ASAP!!!!!!!

My telkom number is: ********** 018

I want answers please!!!!!!!