Poor service and ***** company

Iam having problems with this company since 2021 when I signed a phone contract with them. Each and every month they lock phone for no reason when I call no one is answering the phone no one is answering emails. Even today this point in time my phone is locked for no reason when I call I respond the lady who answered me she told me that my phone is In erreas of R400. I have to pay that 400 before.. When I wanted explanation she just hang up I tried to call again no one answered. Their Customer service is very disgusting please help me as they are demanding 400to be paid before they can unlock my phone.