Telkom Mobile ******* and technically ***********

I have a Telkom Mobile data contract with number ********** 894, account number ********** 51. I have 10GB Inclusive SmartBroadband Data + 10GB Included Telkom Mobile Night Surfer Data. For March and April 2019 this data was depleted within 6 days. In both months Telkom provided me with a usage report. March I understood, but in April there was usage even on days when we weren't home and the router was switched off. I have the wifi password protected and a MAC address filter, so only registered MACs/devices can connect. I've been on teh line with Telkm Mobile a few times and logged a query on their website, but no joy. 2019/04/16 I was on the line for 33 minutes and still couldn't get a manager to speak to me. I was told the anager is Harrison Malunga with email ********** They merely tell me the report they give is all they can see and Telkom does not have the technial expertise to investigate it further and tell me where the data is used, possible site addresses or MACs. For me the data is being "lost" in the network or the Telkom mobile billing is incorrect. And with only 4 months left on the contract is will cost me more to cancel it than keep it. It will be approximately R820 to keep it till expiration, but it will be R800 cancellation fee and R200 device fee = R1000 to cancel, after the initial contract says the device is free. I don't expect Telkom to get back t me or resolve this issue at all.