Internet usage on a stole phoen for R15000

I am hoping I can get assistance here as Im struggling to get one through the CellC consultants. First, my phone was ******, reported to CellC and blacklisted. That was in early March or late February. Come, April 25th, my statement is billed at +R17k. R17K? How in the name of the Almighty can I use a phone for that much? My services are now suspended for a case I expect CellC to help me solve. Whoever is using my phone is uploading airtime for others without my consent and SmartCall is also benefiting as they are using their services. I can only ask CellC to help me in solving this case and to actually suspend all my other contracts with immediate effect and to actually answer their phones. I have been on hold for so long.