Sello from Sales doesn't call customers back

I was assisted by Sello in the sales department, he comes across as more happy to receive a sale but does not return customer calls on after sale queries.

The sign up was not completed, Sello called back to back until I answered, this was unprofessional because if I don't answer it means I am busy, give it an hour and try again. I've left 3 messages asking that he calls me back, the last message was with his manager as well but I am still to be called, Absa idirect has a superior offering however conduct like Sello's does the opposite in increasing the value and world service customer care.