Frustrating Service

For a online school their so out of tune with the reality of life. I cancelled my services as my son wasn't copying with lack of interaction and was starting to get depressed as such I took it upon myself to cancel their services sent communication via email. Nobody acknowledged my email 2 weeks later one of the HODs calls me to ask why my son is skipping school, I forward her the communication I sent and she also doesn't acknowledge my mail. Fast forward to now am getting threats on outstanding school fees, when I cancelled their services months ago and put my child back in traditional school. They don't acknowledge any emails but their accounts division sends never ending statements and threats.