Data issues Night surfer

I have a data contract on telkom mobile. on Sunday 13 sept at 02:00 in the morning I started a update on my computer using my night surfer data which is from 00:00 07:00 so I dont have to use my normal data which is 5 gig, at five I went to check the status of the update and was surprised to see that the download was stopped when i checked, the message was that my data bundle is depleted, which is impossible as i have 15 gig night surfer data. I called 018 180 to find out what the problem is, the lady I spoke to told me that my normal usage data is depleted, I told t that is is impossible as I used the modem in night surfer hours, she told me she will report the matter and somebody will get back to me and gave me ref no ***4. I phoned several times during the week as nobody called me back and everytime the person I spoke to had a different story. Today Monday 21 sept a woman phoned me and told me my modem is on roaming and that is why it took my normal data instead of night surfer, it is the first time this happened, and they cant explain to me how my modem went on roaming and they cant give the lost data back, I am not happy at all I can not leave it here.