Telkom reaping us off

I'm so disappointed at Telkom.,i have a contract with them and today I switched on my router data was finished which I found strange as I did not use it so much for data to be finished by now. So I decided to top up.,when I went to my telkom app it showed I have 375MB instead of 500Mb I loaded. I called them to find out what happened as I just loaded and I didn't switch on the router I used my cellphones data to check on the app if the 500is in yet but found 375 Lerato the agent I spoke to couldn't answer me clearly kept saying they can't see where I went on the internet I kept telling him I didn't switch on the router I want to know what happened to the data he couldn't answer telkom Is reaping us off. And I'm not the only one with this problem.