Telkom pay back our deposit!!!

We app**** for a Adsl line with Telkom. Was approved but had to pay in a refundable deposit of R700. Account was paid up in full when we canceled in 2020. We have been battling to get our deposit back without any luck. Numerous calls. Put on hold and then cut our calls. Went into the branch a couple of times as well and still nothing. Apparently the case is closed without reason. That's all we hear and they investigating. Investigating what??? A refundable deposit means give back our money!!! Telkom easy to take money but refuses to pay back what is owing to us!!!