Telkom Technician stole my data

I reported network reception problems ( ********** 8). A technician was sent to investigate, He came with his laptop asked for my password to my router so that he can connect and “do receiption tests” which I gave to him, not knowing he meant to ***** my 40 GB data. Why I make that assumption is because he is the only person except me who knows the password and I did not change it since he left. He did his tests, told me he is not allowed to reveal the outcome but Telkom will tell me. So he left. Few days after that we on holiday with my family. Next thing we come back my router declares that I have used all my data, which is impossible for us to can have used all that data in one week. Went to Telkom store in Greenstone Mall to report and find out what happened. Log sheet shows my data was been hacked into and used at midnight when we could have been sleeping. I have logged a complain ( ********** 9). How then do you trust their technicians if they are the hacking *******.