Unnecessary delay in processing refund

On the 31 August 2018, travel start had a special where you get flights for reasonable good prices. One had to make a booking and pay on the same day inorder to benefit from the specail. I accidentally chose a wrong return date, this I only realised after I made the payment when I received my iternary. I called travel start immediately and spoke to a consultant who advised me to make another booking and pay again, then cancel the other booking which has a wrong return date. She said one can't just cancel part of the booking as I only wanted to change the return date only. This didn't make sense to me but I went ahead and paid anyway. She reassured me that the money will be refunded in my account as soon as it reflects in their account. I have been struggling to get my money from them ever since. I am not sure what the issue is. I have made numerous phone calls and e-mails but up until today the money is still not in my account. I regret ever making a booking with them. I have never experience such problems when I do bookings directly with airlines.