Please refund and stop charging me for sending me sms for amounts that I am clearly aware are overdue

I bought furniture online on the 23rd June 2019. I asked for a return and a refund, but until this day the status of my order is still "processing" and I was told that there is a backlog in the refunds department and I have to be patient.

What I don't appreciate is that I am supposed to be understanding of the fact that there is a backlog in the refunds department but then then again I receive an sms for an overdue amount on my account of which I am charged. If am going to be charged for reminders for on overdue amounts of which I am aware of then can the least you can do is credit me some interest on the money you are yet to refund.

Please kindly indicate to me with a definite date on when I can expect my refund, its been over a month and that's more than enough