BAD 10GB WIFI SERVICE

I BROUGHT A 10GB BUNDLE SPECIAL FROM TELKOM ON THE 29th march 2018 and received it the sunday 1st of april 2018, and it was so strange that i used up 10GB in one week. and i went in to ask if i can upgrade or cancelled it since i was in the first week of my contract ..and they refused to give me an alternatum for my problem ...and tell me that i can pay a R1800 for cancelling fee , which i was very disappointed in telkom .