Client experience and expectations

Placed a return in Dec 11 and Zando only collected it in Jan 2020. I am still waiting for my refund and when I called yesterday, the agent said that there is nothing they can do but wait for the third party to give them feedback. I asked if it was possible for them to continue with the refund in the meantime as this should not be the client's problem and the lady said there is nothing she can do. I asked to speak to a manager and was promised the manager would call me back but no one did. My experience with Zando is that no one ever calls back. This is a horrible client experience on top of not receiving my refund. How long do we have to wait to get our money back when we have to pay within hours to secure our order?