Lost client.

I hired a vehicle from budget Windhoek international airport. On two occasions. The first 1 was last month on the 17th, returned the vehicle on the 24th as per agreement. Was told the Deposit would be released within 7 to 14 days, now 25 days later still nothing. The staff at the airport are as helpful as they can be, trying to assist. Is this the way budget increases their revenue by keeping clients deposits to earn extra interest?