I paid up their account since August 2020 and the funds were more than the required I thought since I had two accounts with them they'll move the surplus to the other account

I paid up their account since August 2020 and the funds were more than the required I thought since I had two accounts with them they'll move the surplus to the other account. Even after noticing they never refunded me nor move the funds accross instead the funds have been sitting in that closed account since. I received an email showing the surplus I called them asking for inter-transfer was told the only way is to get refund an pay into the other account. Which I did had to email them P.O.P and bank details for where funds should be refunded. Got email that query is resolved but to date no funds back. I called again was informed they await P. O.P, while on the line agent confirms my email with P.O.P is received that she'll send it to them and request refund. That's another week gone. Waited no funds still received. Called again after 3 working days was told refund was only processed the day I called which is this past Wednesday the 4th time I'm following up in 3 weeks and that the funds will be in next week. How many time does it take to process 1 refund? Which all docs are sent in one email?