Telkom not responding

Telkom has been billing me for the amount of R716.70 since November 2018.Many This amount is in respect of two calls made to Belgium. I don't know anybody in Belgium and Never made an overseas call ever. Telkom acknowledged receipt of the query . Ref No. ********** 0. Nothing has been done and now they are also adding interest on the account. There is just no response from Telkom