Debited for a returned router and denying me a refund .

MTN South Africa is really disgusting, they are ****** of note ,they invoiced me twice for a contract that I canceled within 5 days of taking it due to non 5G coverage in my area ,I returned their router and they received it without any faults ,then after that I was billed twice and when I requested my refund with proof ,they played games on me telling me I have no refund .