Mtn home router returned, refund to be paid

I took out a mtn home internet package in January 2025. I went to the branch to cancel the month to month deal and returned the router on 23 June 2025. I handed in the box with the router and all its accessories. Had to sit long at the branch with all the paperwork. Since I paid in advance I'm suppose to receive a refund. I want my one month's advance instalment back asap MTN.